My laptop has been running very laggy lately. During seemingly random times, it just goes EXTREMELY slowly. Furthermore, adaware scans and virus scans simply stop moving in the middle of scanning. I tried running in safe mode, and system restore, to no avail. I tried disk defragmenting, but after 14 hours, it was still stuck at 27%. Now, when i boot my laptop after hibernating, it says there is a data read error, and it must reboot. Do you think it's a virus? Or am I in HUGE need of defragementing? Thanks in advance!

check drive for free space,check msconfig> startup for any unknown files running, also try running scandisk for errors and bad blocks, if firewalls and virus scanners are running, may need to disable or start in safe mode, anylize fragments of drive, if high %, yes may need to defrag and may take a few hours, also check temperature of cpu for overheating to be the cause...:)