"server busy", c:windows\image.dll, about:blank

please help - i have about every guard on our system yet spyware/adware/hijackers are on our computer and i want them goooone. we have: a dell w/ a pentium 4 at 204ghz, 256mb ddr at 333mhz, 40gb 7200 rpm hard, winXP, and internet access via cable. i have pop-up stopper, ad-aware, spybot, start-page guard, avg scan and zone-alarm firewall. i've also done a "hijack this" and just a few things came up which i deleted.
i think part of our problem is that my husband subscribes to pcgamer magazine and plays the "free" disc that comes with each issue. each time we turn on the computer the following errors pop up:
1. 'server busy. this action cannot be completed because the other program is busy. choose switch to" to activate the busy program' (below this are 2 boxes - switch to or retry.)
2. ' c:windows\image.dll the specified module could not be found'
3. whenever i sign on the internet, my homepage is not there. instead, 'about:blank' has taken over. also, a pop-up telling me that i 'may have spyware and click here to remove' comes on. duh.
i have tried removing as many programs from our system that is questionable; however, i cannot remove 'interstitial ad delivery by search assistant'. it keeps coming up "must be connected to the internet to remove this" which i am.
the whole process has slowed down considerably as of late - it takes a good minute to sign on the internet because of the pop-up and other things fighting for our attention. thanks in advance and i hope you stay grumpy...colleen.