I've been dealing with this problem for some time. Almost daily, AutoCAD will crash randomly. First pop-up will say "FATAL ERROR: Unhandled Access Violation Reading 0x0000 Exception at ........"
Every once in a while it will say:
"Your license is invalid. Please contact your local authorized AutoCAD dealer" followed by "This product has not been properly activated on this system."
Some of the triggers I've noticed are one of the following:
-I close a file by clicking on the "x" on the file tab rather than selecting it first.
-while saving
-enterring an x-ref file by right clicking then selecting "open x-ref" rather than opening the file via the menu
I am operating on a 64-bit Windows 8.1 with 6BG RAM. So are the other computers in the office, which do not have this issue. Therefor this cannot be because 'operating system is running out of available memory (2 GB for 32 bit OS) and is shutting the application down' as an Autodesk employee suggested in another post with the same issue.
Please help! This is driving me crazy, settting me back, and unfair considering we paid for licenses.