Why is my computer slow after a fresh format?

chell20013 asked:


I had something corrupted on my hard-drive and couldn’t install most software, including any anti-virus programs. I finally found a trial version online that would install, and discovered I had 26 viruses–after nearly a year without protection, it was no surprise. I still couldn’t install hardly anything, so I saved all my pictures and files to my webpage, and reformatted the computer. I then installed Norton Antivirus, Microsoft office, and the usual games I’ve had on the last 3 computers I’ve owned. I installed all the Microsoft updates, and waited a month before downloading my pictures and files. I waited another month before I felt “safe”. Its been almost 4 months now, and my computer is terribly slow. I have to reboot sometimes 3 times before it will run fast enough to open Explorer in less that 60 seconds. Then the speed is erratic. Sometimes it will be too slow to use in the evening, and then run ok in the morning without a reboot.