No, I do not think that you should disable avast! to upgrade to Win7.
Windows startup.exe does show numerous examples of startup.exe being infected in a Google search.
Avast is likely protecting you from becoming infected. Disabling the protection increases the risk your original operating system will become infected.
- Is the Win 7 CD/DVD upgrade copy legal and clean?
- Are you currently having any problems with your system? Is that why you are upgrading?
