config should be ok. Try reseting you BIOS, press Del while booting and select the restore option.(further controlls are shown in the bios)
Are you getting BSOD? if yes, then update all drivers, and uninstall unneeded softwares, that may cause the problem.
If these fails, put in your Windows install disk and select the 'repair' option, it will leave everything (files, softwares), but it will replace the system files, with the original copies.