Another Anti-Malware Doctor infection

Hello - long time lurker, first time poster. Finally found something that I can't solve from reading other people's problems and solutions!
I seem to be havng the same issues as the poster a few doors down - I had Anti-Malware Doctor, thought I'd removed it, but I'm still getting a C:\WINDOWS\$NtUninstallMTF1011$\mmduch.dll Rundll error on startup, and problems running certain files (I get a popup telling me to run chkdsk). Running AVG which isn't reporting problems, and I've run Malwarebytes which doesn't find any problems.
However, I've been a bit naughty because I usually just follow advice that I Google, and I've run Combofix. This found evidence of a rootkit and also warned that I may have 'virut'. On searching this, I think it may be onto something - it has a fairly consistent filesize and I (stupidly) downloaded something of the sime size just before the infection started.

Any help gratefully received.

Try this: Removing Anti-Malware Doctor?