Kaspersky scanning

[Big]

If I deep scan a file (say, a .zip/.rar file with .zip .rar files in it) with Kaspersky, fully updated to the minute (latest update) and Kaspersky yields me a 'no threats' report of the scan, does this really mean the file is 100% harmless?
Can I trust Kaspersky or should I still be wary of malware creators who somehow hide behavior from the kernel/OS/AV engines, faking to the user that it's 'harmless'?

Edit: it's funny that right after installing this suspicious program I downloaded,
         after Kaspersky's file scan saying it was harmless,
         now after installing it, Kaspersky suddenly red alerts me about a suspicious hidden 'download driver' driver installation. Why didn't it warn me beforehand?

[Allan]

You shouldn't have downloaded a suspicious program, should you? Don't blame your AV (and Kaspersky is one of the best) because you choose to take risks.

[Big]

One of the best? Isn't it the best? I paid quite a bit of money for this suite (fw+av+etc).

[Allan]

Personal opinion. I happen to believe it's the best, but there are others who will disagree. Regardless, it's certainly one of, if not the best.