Trojan infected file 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 understand this may be something to do with Spyware Doctor, so I have unistalled SD - rebooted - rescanned - installed Adaware (for now) - rebooted and scanned and hopefully this has solved it. Still don't know what this 'driver' was though!