It sounds as if you may have acquired some malware on your system, a BHO (browser helper object) or spyware. Internet Explorer has its share of detractors, but it won't crash your system unless it's infected by some malicious software. Using a different browser and adding a firewall will prevent nearly all of this type infection.
right on DaveAtIFG! sounds like a bad case of BrowserHelperObjects or Spy/Malware. You may want to try this little trick. It won't remove the malacious code, but it may enable your computer to operate correctly under non-browsing circumstances.
Go to My Computer -> Tools -> Folder Options Click on the 'View' tab Check the option that says 'Launcher folder windows in a seperate process'
You may also want to try the Mozilla FireFox web browser. It is quickly rising in popularity amidst the large amount of security holes in IE.