Just recovering from a very nasty virus infection on PC which I think is now cleared as Avast, Malwarebytes, Kaspersky Virus Removal Tool 2010 and AVG 2011 full scan all report no faults.
However if I run the rootkit test option on AVG 2011 (Its a new test in this year's version) it reports 6 IRP hooks which it can't remove. I get the same thing on another XP machine which is rarely used for browsing. Windows 7 machines here don't report these hooks. AVG says the hooks *may* be used to hide rootkits, but as noted above, no other application finds anything.
Google shows a number of other mystified users and no clear answer.
If you have an XP machine, I'd be grateful if you could try the AVG 2011 rootkit test and see if you get a similar report. It may just be a false positive, but I'd like to be sure.