Thanks for the hosts info.
I checked the file (was under "c:\windows\system32\drivers\etc\" in WinXP 64b, though oddly enough about the System32 part on a 64bit system), and it didn't have the URLs pointed to the loopback address (127.x.x.x), but did have them pointing to IPs that weren't correct (example: "180.78.122.242" for
www.avast.com, and "105.94.46.61" for just avast.com). When I rem'd them out with the "#" and re-saved the file, I was able to access avast.com and any of the others I tested perfectly fine.
The anti-spyware program I was using was AdAware, and it seemed to work pretty well on an x64 system. I tried the one's you'd listed (minus the AVG one, as it stated on the site it was for x32 only), and didn't have any better luck. Superspyware didn't find any new hits, and Spyware Terminator just found two false positives (that I sent feedback to the company about).
I think the reason none of the programs hit on the issue with the hosts file was that the IP addresses looked legit, unless you already have a database of the correct ones to compare to.
Question, though. To be on the safe side I was considering just wiping the contents (just the address mappings) of the hosts file on my PC, but was wondering if it'd have any negative consequences to doing that. As of now it doesn't seem to have any issues with a bunch of the lines being remarked out, but I wanted to be sure first.
Thanks for all the help, btw.