Let's run some tests with freeware to see if your hardware is good: type "dev" in Start Searh box, open Device Manager, look at Disk Drives, google the long serial string. This will tell you what HD make you have. Then find the HD maker on this list and download the HD diagnostics to burn to CD:
Hard Drive Diagnostics Tools and Utilities (Storage) - TACKtech Corp.
Double click on the ISO file and Windows Image Burner will burn it to CD. Now reboot computer and run the full diagnostics scan. Copy down what it reports and post back.
Next download and burn to CD the same way memtest86, run test for 5-6 passes or overnight. Post back what it reports.
Memtest86 - Download Page
Check for infection now by downloading and installing Malwarebytes, update and run Full Scan:
http://www.malwarebytes.org/ Then install MS Security Essentials which is the best free AV:
http://www.microsoft.com/security_essentials/
Go back to the Event Viewer>Admin View and google the repeat Critical and Errors. Google some of the text and ID# to find out how others have solved the errors. This is how you learn about your computer and troubleshoot its problems. When you see a pattern of repeat errors, post back their text and ID# here too and we can help you easier since you'll already know more about them.
Next go Start>rightclick Computer>Properties, click on WEI score link, at top of Advanced Tools page look for cued issues to resolve. Then google repeat errors in Performance log and Generate a System Health Report. Look for problems it reports.
Type "Prob" in start Search box, View solutions to problems found that have been already sent to MS which you may not know about. These are sometimes also cued in the Action center with the flag in the bottom right system tray.
Next run
http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html
There is no reason to reinstall again. You should run a
http://www.sevenforums.com/tutorials/3413-repair-install.html?ltr=R instead, unless you haven't tried wiping your HD yet. if not, then you can consider one last reinstall to overwrite any possibly infected or bad code using this method first:
http://www.sevenforums.com/tutorials/91339-ssd-hdd-optimize-windows-reinstallation.html
Don't become discouraged, this may be one of the best learning experiences you have in life and you will end up knowing so much more about your computer you'll be able to help others.