Start Search cmd.exe. Right-click and Run as Admin.
Type chkdsk c: /f /r
Schedule for reboot. It will take an hour+ probably.
Even if a Service appears started always right-click and Restart it.
Start Task-Manager and click Processes Tab.
Right-click explorer.exe and End Process.
Click File New Task (Run), type explorer.exe
Try an old Restore Point
Control Panel > System and Security > System > System Protection > System Restore
Find any Vista discs if you have them for Repair or Clean install possibilities.
What Make and Model of computer is it?