Yeah, I could see 12.04 being the cause of our problems.
To be honest, if the virus messes up the computer badly enough to need a pxe boot scan to actually remove it, I’ve found it saves time to just reimage the machine (we make use of a lot of network storage, so losing files is almost never an issue).
I’m actually not sure about how well ClamAV works in regards to detecting and removing viruses, but maybe that’s for a different thread.