Wow. This could be any number of issues from hardware to software.
Hardware--it could be your hard drive failing; it could be bad memory; it could be a bad power supply. There are probably other possibilities.
Software--could be corrupted registry; could be a virus or malware; could be a corrupt windows installer; could be a failed windows installer program (windows cleanup tool); or could be some failed uninstalled software. Again, could be many other possibilities.
1st steps--check out hardware possibilities; hard drive, RAM, power supply, etc.
http://www.techsupportalert.com/best...ng-utility.htm
http://www.techsupportalert.com/node/84
http://www.memtest.org/
2nd steps--boot into safe mode and run some anti-virus and malware scans
http://www.techsupportalert.com/cont...escue-disk.htm
http://www.techsupportalert.com/best...e-programs.htm
3rd step--download and install windows clean-up tool. Then use it to uninstall any unneeded programs or clean up failed installs.
This is a good place to start.