Use Startup Repair to get to a DOS prompt (to run CHKDSK /R /F )
Most systems can get to Startup Repair by tapping F8 just before the Windows Splash Screen shows up. If its there, you'll see an entry at the top for "Repair your computer"
If you don't have that option, then you'll have to boot from a Win7 installation disk in order to access Startup Repair. More info here: Startup Repair: frequently asked questions
If this doesn't help, then post back for some more suggestions.
While waiting you can try the free diagnostics here: http://www.carrona.org/initdiag.html
Also, I've sent you a Visitor Message