Just did a spell check on a document in 10.0.1. Dialog freezes for 30 seconds then a full crash. Front end and kernel shut down by windows. On Win 7 x64 and Mathematica 10.0.1. Save your work first!
I have the same problem, Windows 7, Mathematica crashes when I invoke the spell checker.
I am not seeing this issue on OSX.
I did indeed have text cells as introductory material to sections.
