The Password Protected thing, is just because the archive is protected via Encryption. I have thousands of ZIPPED files Avast! cannot scan on my system because of the High Risk potential involved with them (Zipped Viruses). (Curious Hands live in my house too, so leaving them out = Bad).
Regardless, as for the Sliding issue, I have no clue. Sounds funny though. What Avast! Program are you using? Also what OS (SP and Bit)
Edit: Seeing the Password Related File are related to Spybot, I have some comments. It isn't uncommon that all AV's protect their files.. How else would they defend themselves against a malware attack? Also, SB S&D (SpyBot) is very outdated, and offers you little, to no protection against the "Latest and Greatest". Malwarebytes is drastically better and faster.