You can open up msconfig (start->run->msconfig) and choose the "Diagnostic Startup" radio option to limit what is loaded to the bare essentials. Reboot and try Flash. If it works then something in your user account is definitely corrupt and we really can't tell you what that is beyond run normal antivirus/malware/spyware/etc apps and hope it finds something.
Remember to run msconfig again and set it back to "Normal Startup".
If it continues to crash, try saving your files in a new location, hopefully outside your user folder (c:\users\yourusername). Like make a folder c:\test and try your files there to see if you have some user corruption going on in your user folder.