See if you can start the computer in safe mode and if that works, try running the Seven Forums diagnostics tool included below in a crude link. http://www.sevenforums.com/attachmen...ostic-tool.exe
The posting instructions are at the top of each thread, but basically run 8 tests that will automatically create a folder on your desktop. Zip that folder and post it back in this thread. This will help the volunteers diagnose your problem.
Hope this helps. I'm going through the same thing. Stay sane and good luck!