Hey Yanto,
Thanks for weighing in. I've performed all of the above already, with the exception of the boot time scan, which is apparently not supported in Windows 7 x64. I lost the explorer file brower for a while, but it seems that Dr. Web has managed to repair it. C:\windows\explorer.exe still shows up as infected with Bamital.X with Avast, however, and so I expect the issues to recur.