Now Windows XP users has a good reason to upgrade it. Undo works just in MMA 10! :)

Microsoft has stopped supporting Windows XP in April this year, about 12 years after it has been released. It's not receiving any more security updates. For this reason it's probably not a good idea to keep using it.

Since then many software dropped support for XP.

Mathematica 10 does not support Windows XP, but Mathematica 9 still does (in case you don't have the option to upgrade the operating system).

This seems shortsighted since estimates are that at least 25% of all desktops and laptops running some version of Windows are running Windows XP. Anecdotal evidence suggests that those on XP do not plan to move to 7 or 8 until the need arises to replace the current machine.

Sorry. If you can't edit the duplicate post, let us know which post(s) you want deleted.

One of the reasons I left this post up is to make it clear that there is a bug with posting (so the bug can be fixed more easily). Now I see the same thing happening with other posts, e.g. the one here

http://community.wolfram.com/groups/-/m/t/294368?p_p_auth=5sFXRgOc

by Neven Golenic, is affected by the same bug. (It appears to repeat the text of the post it is replying to.)

(The other reason was that since I only had access to an iPad at the moment, I couldn't fix it, and after the post has been up for a while I needed to add an explanation of why this happened.)