I'm assuming this malware is some kind of downloader, because every time I run an avast bootscan I come up with fifty-odd infected files in the Windows Temp directory, with names along the lines of "jar_cache[number string].tmp", and usually a few in the java cache directory too. All are infected with various flavors of Agent:Java-[lettercode].
Try this

TFC - Temp File Cleaner by OldTimer
http://www.geekstogo.com/forum/files/file/187-tfc-temp-file-cleaner-by-oldtimer/
TFC requires a reboot immediately after running. Be sure to save any unsaved work before running TFC.

then continue with attaching all logs from this guide
http://forum.avast.com/index.php?topic=53253.0

Essexboy will have a look tomorrow
he is usually in here around 08:00pm - 11:59pm UK time