A couple of updates ...
Turns out it only disables my firewall, not antivirus. These are the scans I performed:
adware: none found
viruses: none found
trojans: none found, BUT is said that I had an open port (#5000), which is a trojan port. It said that the possible trojan is "Blazer 5."
How do I close this port? Seems like the firewall is not doing it, it usually stealths them.
Also, if I cut off the internet connection to the PC (connected via PCMCIA card), this problem of explorer freezing up goes away. But as soon as I enable it, it comes back.
Have too many files and settings on the PC, wouldn't want to reformat. Also, is it safe connecting this PC to a router and tranferering files to another computer, will it infect it?