I have two W7 SP1 x64 computers and have never had the problem that you are referring to.

  1. When did you get the W7 x64 system?
  2. Did it come with an Anti-Virus program?
  3. If it did did you uninstall it and how did you uninstall it?
  4. Did you uninstall it before you installed avast!?
  5. Which version of avast! did you first install on your computer?
  6. With which version did this problem first occur?
  7. What version are you on now?

Thanks