Well, define that «without Avira»! Uninstalling us usually as useless as using additional tools like CCleaner. If,an removal too by Avira themselves may remove it totally.
Next, the mantra not having 2 (or more) anti virus tools… Note: I did not closed that sentence with the word ‹running›.
If you have just the scanner element of an anti virus tool, that shall not bring up problems, except false positive when each one scans the signature file of the other one.
But - it is ridiculous not to use a shield. So one shield and more scanners shall coexist. So, what do you expect from that? Do you surf to bad pages, download silly things and then scan the income files?
A shield is the one to trust. I never need a second scanner to inspect strange files for I know where that file came from. Only when I get a computer to check up for all bad things, the I set in some scanners, and usually MBAM tells me if there is something to repair or to format.
Up till now it seems like I've reinstalled Windows over 40 times (in 3 years).
I'd installed [note: no re- in front of…] XP 2004 and never again (and quitting 98 3 yeras ago on an other machine that day and never again).
So, sorry, to me you crash your OS by what reason ever, an you do attempt to learn (anything) by your mistakes. 2 AV tools are an indicator as well.
I'm quite sure not to be able to help you…
Eric