PC locked since update

Since the last update/restart my pc (Win98) cannot get past c prompt. The only clue I have is: “Teefer.vxd: Invalid vxd dynamic link call to device nr 28, service 800A”
This teefer file refers to Sygate firewall. I have tried all at Sygate but no info available. I’m asking for help here because I lost my computer the moment I rebooted after receiving the request from Avast (program update?) - 27 May 2005 11:28p.
The wininit.bak file is the same date and time since my problem started and it only mentions Avast update within three lines, nothing else.
It boots up very neatly and I see the Windows screen for about 7 seconds. That is when it reverts to the c prompt. Even holding down Ctrl and then selecting the Safemode option will not allow me into Safemode, reverts back to c prompt. I’ve done the option of step-by-step but my computer knowledge fails me to make any rational decision. It is when I type ‘cd\windows’ & Enter and then ‘Win’ that I get the fatal teefer message.
Is there a way to stop Avast from loading during the bootup stage? I have access only via DOS.
Been using Avast Home for about 3 yrs without a hitch, thus far, saved me many a times.
Very very desperate, any advice?

In fact, this is a Sygate problem… the fact of avast! was the ‘last’ program due only to an update atempt, normal and legitimic.
Maybe this help: http://www.hackfix.org/software/uninstall/sygate.html
Google Teefer.vxd and you’ll find more.

Thanks Tech, I’m currently slowly working my way thru the DOS startup files hoping to trace the problem. As I mentioned I’ve only got a c prompt to work with and therefor uninstalling Sygate is impossible.