The database is OK; I don't think there should be any login in the .ini file, but it shouldn't be connected.
The thing is that avast! doesn't really do anything special - it just tries to open the file, just like any other program, and if the opening fails (meaning that Windows doesn't allow this process to access the file), it returns the corresponding error.
So, this is really strange... it shouldn't happen, unless:
- the currently logged-on user doesn't have access rights to read these files
- there's some other low-level program running that somehow interferes with avast! access... but as I said, there's nothing special about avast! scanner. If it was avast! resident protection, OK, maybe... but the on-demand scanner is really just an ordinary tool.