Stopping Unstoppable Malware?

A frustrated troubleshooter asks: "I've recently been asked to fix a friend's computer, and for once, I'm stumped. There is a piece of malware on his computer that puts up Aurora popup windows. Neither Spybot nor Ad-Aware detect this, so I've had to try to manually clean the system. However, the files re-write themselves, making the malware grow back as fast as you can remove it. The only "solution" is to run an uninstaller written by the people who wrote the Aurora pop-up itself. Has anyone dealt with this particularly painful piece of pop-up programming, and if so, how have you successfully removed it?" What other pieces of Malware have you found that was difficult to remove? Aside from using programs like the afore mentioned Spybot and Ad-Aware (and others of their ilk), what other methods of Malware removal have proven to be the most successful?