Just updated, then ran Spyware Doctor, yielding 12 instances of "Block-Checker". What is block-checker and does it have anything to do with selecting "appear offline" (even though I'm actually online) as an option when using MSN Messenger?

Block Checker supposedly lets you see if you have been blocked by someone else on MSN Messenger. Its fairly new and is considered malicious. It constantly sends a link to all your contacts for them to get it too.

You may want to submit a HiJack This log for our team to look at. See How to submit a Hijackthis Log. Mention Block Checker in your post if you decide to submit a log.