Great, thanks for all the info. Iam not really a fan of those "tune up" programs like system mechanic. Most of those tweaks can be down with Window utilities and much lesser intrusive software. Some of the results they claim they can make are ridiculous also, its all a bunch of fluff really.
The best thing you can do is uninstall it via the add/remove programs panel.
If system mechanic has a antivirus component in it then it would cause problems if another AV was installed. Plus for AV there are much better options.
You mentioned Norton. Must have been installed at one time. Luckily Norton makes a uninstaller you can use that will remove any leftovers a ''regular" uninstall left behind:
MBAM and AVAST running at the same time will be ok. Ones for malware, the other for Virus. One thing you might check is if both monitor for malicious websites you may want to disable this feature in one so that both arent doing the same monitoring. It may cause a conflict or chew up system resources. Just experiment first with both as is and see how it goes.
As far as other logs I think disabling system mechanic pretty much cleared everything up.