Windows 7 64 bit with 64 bit Blender
Nvidia GTX 750 Ti
Broken: (example: 2.73 b4d8fb5)
Short description of error
Blender crashes sometimes when using the edge collapse operator and using undo after it. It also looks like the vertices were displaced randomly just before the crash.
In the uploaded file, I've got a simple subdivided plane with a solidify and a subsurf modifier on it. (Because that's what I used in my project where it happened)
Exact steps for others to reproduce the error
Open this file:
Click on "Edge Collapse".
Press Ctrl + Z