I'm running into the same problem here, a whole list of suspected rootkits in the spoolsv.exe and spoolss.dll files, mostly in the Microsoft Document Imaging (mdigraph.dll, mdiui.dll, mdippr.dll) and the Software Distribution folder for printer files and updates. I've run several online scans, Spybot, SUPERAntiSpyware, and the Sophos Anti-Rootkit scanner, all of which found nothing. After reading this thread I opted to choose Ignore, and Don't notify me again, but then Avast tells me it detected a virus in memory and wants to scan at reboot. I've allowed this to happen twice, which found nothing. I told Avast not to scan at boot once but Avast froze, eventually it continued scanning to completion (including the report containing all the erroneous rootkit detections). I then exited Avast and rebooted so I could run the scan again, which found the same supposed rootkits, even though I'd told Avast to ignore them and not to notify me again.
This is bad news for Avast. I hope you get this problem fixed soon. -kd5-