Never seen so many General protection failures!

Just downloaded latest version (7.4.2a) onto my Windows 2000 system,and the product's "About" screen says it all.
So far I've launched the program 42 times and it's failed 19 times!! Failures usually occur when opening files (midi files + some of the mus file samples), but also when trying to use export (WAV). Either the application vanishes without trace, or it comes up with a type C0000005 exception with addresses such as 77FCA8AC, 77FCBFE1, 77FCA778, 77FCA776,... But then when I restart and try exactly the same open/export again it works fine, but then dies on something else later.
I can't believe the product can be this bad, so could it be something wrong with my system - although I have so say that all other software seems to run on it ok!
Anyone else had similar experiences??