If this is a virus/malware issue and If your issue is still constant i would Try obtaining a linux live CD from a useable computer such as a family members pc or neighbor/friends pc. Ubuntu should serve fine. This would eliminate the issues caused if they are pure windows based as the virus/malware or such most likely wont be cross platform. Other then this the least i can say is a full format if you still have your backup disks for your PC or a copy of windows. This is of course if your infected and your current virus protection isnt helping. There are many alternatives such as bringing it to a best buy or computer repair shop but you may easily be paying more then a 5-6 year old PC is worth on repairs. The greatest thing i ever did was purchase my own copy of windows. The price is high but when you get more issues than you can solve BAM reformat and your golden.