Does it freeze in Safe Mode?
Vista Advanced Boot Options
http://techblissonline.com/vista-advanced-boot-options/
If not see if you can isolate a third party cause, perhaps a security program that is scanning the Control Panel when you open it?
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/default.aspx/kb/929135
You could also create another user and login to test from that.
Try running ChkDsk to check your drive for errors. Right-click your Drive icon/ Properties/ Tools/ Error Checking. Try it first by not checking either box (this will run it in a Read-only mode) to see if it flags any hard drive or file problems. If it does, restart it by ticking both boxes, and rerun it to allow it to attempt to fix any found problems.
When it freezes are you able to access the Task Manager to see which Process is using most or all of the CPU?
Windows Vista's Task Manager: The harder-to-detect changes
http://articles.techrepublic.com.com/5100-10878_11-6161050.html
Links that mention Vista are suitable for Windows 7.