Trojan Infection removed what now?

First time I have ever I have had an infection notice! I booted up my PC - Acer T180\Vista SP-1 - this morning to find an AVG notice:

Trojan Horse Small AOQ on file:

C:\Windows\system32\Drivers\mchInj\Drv.sys

I clicked on 'heal' but told file couldn't be found and the notice closed. I opened AVG - AVG Free 8.0 - and removed the 'infection' which I assume means the file is deleted. I then ran an AVG full scan and nothing fou7nd. What now? I don't recognize the driver, not sure whether I need it and in anycase I don't have a Vista installation disc - only a recovery disc that was made when I bought the computer. What next, if anything please?

I would reboot and do another full scan if you have not yet done that.

I have already done that - the san revealed nothing - but now after another reboot, I received the same message, so I this time I clicked on 'remove to vault' - but looking in vault it is not there! Maybe Vista will not allow it's removal? This is obviously a driver that opens on boot up, but on doing a Vista search, it cannot be found!.

A did a quick google on this and the main cause seems to be a program called spyware doctor - do you have that installed?

Yes I do have the basic version - free - of Spyware Doctor installed!!

That will be the cause.

Many thanks, that was very helpful. I have rebooted, rescanned, uninstalled Spyware Doctor, rebooted, installed Adaware (for now) rebooted and full scanned and so far everything OK.