Hello ... I'm new to this forum and come with baggage.

I first started seeing indications of a problem a few weeks ago and tried to attack them by seeking remedies for each individual problem, eg, blank Firefox windows, missing files such as rundll32 and both the NOD32 and COMODO GUI modules, etc etc.
Neither MBAM nor NOD32 found anything. SAS Pro was prevented from running because of a buffer overrun in its executable. Because I spent a great deal of time searching forums for answers to specific problems and because a few times everything worked okay for a few days, a lot of time has passed.
I continued running the AV programs and, for some reason, SAS Pro was finally able to be updated and run. It found 1,403 file threats in 38 Adware, 54 Trojan, 57 Malware, 207 Rogue, 15 Rootkit, and three Dialer categories, and one keylogger!! All this from one infection?!
Although SAS Pro cleaned things up and has run clean several times (along with MBAM and NOD32), there remains a problem - I'm not able to get a network connection and I believe the problem lies within the PC.
I have two PCs; the infected primary is hard-wired to a Linksys WRT54GL router - the secondary PC and printer are wireless. The primary PC cannot access the internet, the printer, or the secondary PC. The secondary PC cannot access the primary PC, but can print and access the internet. There are no error messages other than the standard Firefox/IE message when it can't access a site and the icon in the System Tray is emblazoned with an exclamation mark indicating no connectivity.
The latest detector I ran was SDFix which found and deleted a Trojan in a TMP file, but the problem remains.
I hope someone here can offer some advice.
Thanks
EdP