most likely hardware issue, drivers are outdated[or bad], or memory issue.
get those utilities from guru2d or whatever that wipe out previous video card drivers- reboot -- then install new ones from nvidia.com or from your manufacturer(LIKE HP, DELL)
if that doesn't work, do the full memtest scan to check memory is your problem.
& if it still crashes, uninstall wc3, run CCLEANER, Re-install direct X, re-install wc3, do update from bNET and then check if you still are crashing.
you can also try to open up your case, take out your memory 1 at a time and blow slowly on it, clean the area and switch the slots around.