Inventor In FDS 2013 Crashes when using Ctrl+Z

[#1]

Hello Dear Frnds,

I had around 10  crashes in 3 hrs with Inv 2013 while doing a sketch on a part face which in an assembly.

My undo file sizr in Application options is 4095 and I dont know why it is crashing, can you guys please fix this issue.

Thanks

AD