Well some viruses don't hide as well in safe mode because safe mode w/o networking has limited services and startup programs. For an even better check, download and run TDSSKiller & 2 or 3 versions of RKill and run those in safe mode prior to running the full scan. TDSSKiller looks for rootkits and RKill looks for programs that started even in safe mode and Kills them (stops their execution so the A/V can see them). Links to those are available in our
Freeware DB. And I'm not saying you do have a virus, just these days it's a good idea to check.
System File Checker is SFC.
Chkdsk looks for bad sectors on your hard drive, which is also good to run if you think the HD may be going bad and corrupting your files, but it won't fix the files if they are already damaged..