Vista Hangs up

My Toshiba Laptops keeps hanging up. The Vista Premium Home OS has been reloaded but I am still encountering the same problems. I am running Verizon Security suite and when I run the Virus/spyware scan, it always stops at C:\windows\system\config32\regback\system. I get through about 50 % of the scan. At this point at the if I point the mouse toward the bottom of the screen I get an hour glass and it's hung up. This is very consistent.

Please help

Thanks in advance