Weird scan reports/way to short scans?

Hi! So I just reinstalled windows and almost as soon as windows was installed and filehistory was in the middle of being copied from my backup.
Windows defender says a file had(s) a trojan, which kaspersky antivirus didn’t report on. And several online scanners also missed.
So I installed Comodo antivirus and didn’t take long before it started reporting a few files containing trojans.
Which Kaspersky missed. Ok so they are slightly different at behavior I believe. No big problem there.

But here is the fun part, it scanned a 7zip file and said a file contains a trojan, and I extract out the file from the 7zip archive
and scan it with Comodo and it states it’s clean no action needed. I ask it to scan the archive and now there is a virus?

So I ask the antivirus to scan a folder with all kinds of files (texmod, resolution hacks for need for speed underground 2, most wanted 2005)
and what not. And the report comes after 00.00.02 no threats found.

This makes me wonder, can I trust Comodo to protect me or should I doubt it’s reports?
I did set heuristics to medium.

OS: Windows 8.1 64bit

Attachment contains Comodos antivirus report in *.htm

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