Inventor quits on Me!

[NeoSwoosh]

I'm having a huge problem:Inventor (Ver5) used to work on my pc no problem but ever since I Installed Inventor 7 it would work and after a few days e.g 3 or 4 it comes up wit an error message.First it was a memory error,I reinstalled windows and thats all that works but please does any one know a way to fix it thats easier!I can go into inventor but as soon as i create a new part windows says it has encountered a problem with inventor and I have to exit.Please any help would help!