I had a similar flakey problem and ended up communicating with Mathematica Support who suggested the following:

1. With Mathematica open, select 'Preferences...' from the 'Edit' menu. Then select the 'Evaluation' tab in the window that pops up.  Try hitting the 'Reset to Defaults' button and see if the computation will work then. 

2. If the above does not resolve the issue, try resetting Mathematica to its default settings.  For instructions on doing so, please see     http://support.wolfram.com/kb/3274   The first item did nothing to help at the time BUT the second one not only fixed my problem then but recently also another instability problem with using the Graphics -> Drawing Tools. - That's 2 for 2 in correcting instability problems. Only problem is you have to erase your preferences file (save first !) and re-register your product -not a big problem and it is soooo nice to get rid of that instability or buggy behavior.

A 10.1 would be great if the company undertook to fix ALL outstanding bugs and introduce no new features.

Well, we have been promised a desktop version 10.0.2 "soon", since October or so. So it will come, well, soon. Like PlayerPro 10, also promised soon, this year, which proves that they are indeed working to fix bugs and have nice new features.

What do you mean by "released"? It still says "BETA" on the programming.wolframcloud.com site. Some things already work very nicely, but, e.g., ListPicker, or uploading an Excel file does not. Also, while JLink works, MathLink and LibraryLink do not work on the cloud, which is unfortunate, but understandable for security reasons. Of course one would want to fix this in a private cloud version. But that version seems to be not available yet, hopefully soon.

Multiple undo is nice (though has been there for a long time for proper .m files in Workbench or IntelliJ or vi), but if this is the cause of crashes I will switch it off immediately once I use more Mathematica 10, which is supposed to be released soon (10.0.2, I mean).

It would be great if Wolfram Research could provide a means for users to provide Mathematica projects that are more involved than Demonstrations.

I agree absolutely. We all need some basic functional we can rely upon. Currently we have some extremely limited reliable basic functional which seemingly was not extended since the Mathematica version 3.

Thanks for the information. I was not aware of some of these options.

Once a Mathematica 10 compliant CDF player has been released, I will check them out, using my wife as a beta tester.

Have not noticed stability problems in V10 on Yosemite and prior to that Mavericks but admittedly did not use it much due to the amount of bugs present and the lack of Player Pro. I am still on V9 95% of the time but want to shift 100% to V10 when these issues are fixed because I like some of the new features. It remains a source of frustration that bugs go unfixed for multiple versions. In the V10 installation I have tried (10.0.1) there are bugs reported in V7, V8 and V9 still present.

I wonder what users think about having multiple Menus on multiple notebooks?

What I really like about the new-in-v.10 multiple windows interface is that it provides a workaround for the long-standing bug of empty list of opened Notebooks in the "Window" FrontEnd menu: now the individual Notebooks are also available from the Taskbar and I no longer have to rely on the FrontEnd menu.

Just presenting a "palette" of choices (such as PlotThemes) to users is not sufficient. It vastly underestimates the true power of Mathematica with its active calculation and dynamic controls.

I agree absolutely. The PlotThemes-style of development feels like step backward in the design of the system: it does not expand the possibilities but provides a limited number of hard-coded choices which are already simply outdated in their design (and always will for the obvious reasons!). It is not an expedient direction of development. What I expect in the future versions are new ways to construct graphics from other graphics. In particular I lack vector CropByMask command which would allow to crop a vector object by some vector mask defined, for example, as a Polygone (keeping everything in vectors of course!). I also lack the working FullGraphics function (which starting from version 6 simply does not work in the most of cases). I also feel that the Ticks functionality should be completely redesigned to allow much more flexibility: easy control on the distance from tick marks and the axes/frame, built-in functions for generating Ticks specification with at least that functionality which currently provides the CustomTicks` third-party package (what a shame that for such a basic task we still have to install third-party packages!).

Mathematica 10 appears to have caused more problems for Windows than for Mac. I considered it bad enough on Windows 7 that I reverted back to Mathematica 9.

I wonder what users think about having multiple Menus on multiple notebooks? It may be connected with the new Undo and at first seems like a good idea in itself. But it has one major problem: it's no longer possible to minimize Mathematica with one click as in previous versions. One might want to do this to temporarily put Mathematica aside and make screen room to work on some other task.

There is another problem with this concerning the use of side windows. Using a side window is useful if you want to present a display that remains in view while scrolling the notebook. There are two principal types of side windows, notebooks and palettes. If you want to minimize Mathematica you now have to minimize all the notebooks and then the palettes are automatically hidden. You can put dynamics and graphical displays in palette windows - except that you can no longer rotate 3D graphics with the mouse. I did submit a bug report and notebook and it was sent to the developers. I hope they fix it in 10.0.2.

Another concern that I have is stability over Mathematica versions. Beyond the use of Mathematica as a super graphical calculator scratchpad, I believe that a natural usage would be the writing of literate notebooks and applications consisting of literate notebooks, packages and documentation. Mathematica has tremendous advantages in this area but I don't know if it's very much exploited. These take much more work than just scratchpad calculations and a lack of long term stability may mitigate against it.

One trend in Mathematica that I find disturbing is the introduction of more "set-piece" high level routines without easy usage or even access to lower level routines. (One example might be graph theory, which combines algebra with graphics. There are many other rough patches, many of them that revolve around graphics.) It is all right to have "set-piece" routines for common things that users do. But they should be built on lower level accessible routines.

Just presenting a "palette" of choices (such as PlotThemes) to users is not sufficient. It vastly underestimates the true power of Mathematica with its active calculation and dynamic controls. You can't just present users with a palette of animated (say) 19th and 20th century graphical presentations. The universe of concepts or data that one might want to present is too large and the possible methods of presentation too great. We have no idea what great new techniques might be invented. Users need easy methods to build these up using primitives. It should be more like writing on a sheet of paper.

I've had this problem too. If it's caused by Undo (I've thought of this also), it would help if there were a command to clear the Undo cache, that could be used occasionally during a process (such as, in my case, a long sequence of non-local image transformations) you're afraid might cause a crash.

(Note that occasionally saving the notebook doesn't help much, because it's often during a save that the crash occurs.)

John,

The spell check crash in Mathematica 10.0.1 has been reported to support@wolfram.com (and it has been fixed in the upcoming Mathematica 10.0.2 release).

I am using windows 8 and it is fine. Looks like something is really wrong with higher version of windows. Ulrich Mutze, I think you should contact Wolfram help center.

Actually the note was meant for John McGee ;-) . And, yes, the crash reports are kind of like looking at the insides of sausage and trying to figure out what animals contributed....

It has been stable for me as well (OSX).

But, if you are able to create any reproducible crashes I hope that you reported them as bugs to WRI.

Perhaps you could tell what OS you are using. I am using OS X (10.10), and see none of your symptoms. I have had a couple hard crashes (sent info to Wolfram Support), but re-opening the notebook was successful.

From a recent virtual event, someone at Wolfram indicated that there will be a 10.0.2 update "soon". Perhaps this update will resolve your problems.