I also don’t have full confidence that it was a false positive, but it isn’t being detected in an active/working file, rather in what I would say is now a redundant uninstall function. That is where my being not being unduly concerned comes from.

If as you said you are unlikely every to require a roll back to pre service pack, then removal of the file would remove any nagging doubt that something in it might be infected. If however, you chose to use that file to revert to a pre service pack state then you may have an infected/suspect kernel32.dll file in use. This possibility would make me even more inclined to remove the uninstall service pack file.

However, it is your system I can only offer advice on what I would do, you have to choose what you would do.

Well you could start with some information like the malware name detected, the infected file name and its location, e.g. (malware name, C:\windows\system32\infected-file-name.xxx) ? Check the avast! Log Viewer (right click the avast icon), Warning section, this contains information on all avast detections.

From that it might be possible to find some information, but without it impossible. However with the multiple issues going on in this topic it would probably be best in a topic of its own to avoid further confusion.