Then, most likely, the password protected archive is not present in PSI installation on the other machine.
You say it started all of a sudden - that’s because PSI downloaded that file one day. It’s got nothing to do with the version of avast! (the archive processing code is inside the virus definitions, so it’s irrelevant whether you have avast! 6.0.1289, 6.0.1352 or 5.0.something - it’s identical code in all the cases, and even though I can’t say for sure what kind of archive that is because it’s impossible to say just by the screenshot, I dare say the code hasn’t changed for quite a while).

So, I don’t see any issue here - Secunia folder (now) contains some password-protected archives… that’s all.