Greetings, and my sincere apologies for the very lengthy narrative.
I have a laptop running Windows 7 64-Bit Premium Home Edition. I've always used Avast as my anti-virus, along with Malwarebytes Anti-Malware. Last week I ran a routine full system scan with Avast, and the end result was no infections found, but it also said that a large amount of files could not be scanned. I ran the full system scan a few more times and kept getting this same result that a lot of files could not be scanned (dozens, if not into the 100-200 range). This was very out of the ordinary, so I downloaded two more antivirus programs to perform full scans and see what they came up with. I realize now, after reading many other similar topics after the fact, that you should not run more than one antivirus program on one computer, but I did not now it at the time. I also ran MBAM, but it found no infections.
I installed and ran a full scan with Comodo, but it said I was not infected, and did not state that there were any files that couldn't be scanned. The second program I downloaded and ran a full system scan with (including rootkits) was AVG 2015. When this scan concluded, the report said that it found and fixed about 19 threats, and one other that it found but could not fix. The one it could not do anything about was an infection of my machine with Inline hook win32k.sys. I could not get the location of where it was located, and couldn't really do anything else other than to close the program. Then again I'm new at this, so this my have been a grave error not to try to get more information on it somehow.
I did some research on that specific infection, and found that there were other people out there who had Avast and AVG at the same time on their machine as well, and when they did a scan with AVG, it also returned this same infection result of Inline hook win32k.sys. This is also where I read that you should not have more than one antivirus program. Thus, I proceeded to uninstall Avast and AVG. After this, I ran the Avast Uninstall Utility in safe mode, as prompted, in order to fully get rid of it. Then I ran the AVG remover (not in safe mode) to fully get rid of AVG 2015 (not sure if doing it in regular mode is bad? I forgot to since it didn't prompt me to do so). It was at this same time that my computer also began to run noticeably slower, especially at startup after the various times I had to re-start when getting rid of the AV programs. One very odd occurrence that I noted was that right before my Windows password screen came up on two separate restarts, which is right after the pulsing Windows symbol screen, my screen got darker very quickly for a few seconds then back to normal. This had never happened before. Not sure if this is relevant, but was noteworthy as I had never seen this.
After having gotten rid of Avast and AVG, I then proceeded to download and install only one single antivirus, Panda Free Antivirus. I updated the definitions, and started a full scan. Before it hit 10% completed, I had to stop it because I was going to work. It did say that there was one threat found (tracking cookie), but I ended it and shut down. Next day I ran a full scan with Panda again, this time completing it, and the results were that I had no infections.
The previous scan with AVG 2015 that found the Inline hook win32k.sys infection still bothered me though, so I uninstalled Panda, restarted, downloaded and installed AVG once again to see if it would find that same infection again. I ran a whole computer scan (rootkits too), but this time it came up with zero infections. I also ran MBAM a few times and it also found nothing. I then ran the Microsoft Safety Scanner overnight, and it also found nothing.
So, as of today my computer seemingly is not infected according to these latest scans, but as stated before, it is still running very slow at startup. Sometimes when I go on the internet using the Chrome browser, it sometimes takes way longer to process page requests than it did before, and sometimes I get the "Page cannot be found" message. It made me wonder if I should uninstall Chrome in case that got infected as well.
Lastly, I ordered from Toshiba a recovery DVD for my Windows 7 (did not come with one from the factory, only pre-installed) so that in the event that I don't have an infection, I can wipe everything, do a clean install, and start from scratch.
My question to the professionals on here is if you have any advice on how I can check to see if I really do have the Inline hook win32k.sys infection lurking in my computer, or any other infection that all these scans couldn't find for that matter;
Or, if I just got a false positive (maybe my Avast infection quarantine vault triggered it?) and if I maybe simply bogged down my laptop by foolishly downloading all these antivirus programs in the course of 2 days. Another question is that if my Avast had items in quarantine (I honestly cannot remember if it did or not), would uninstalling it unleash those items back on my PC, or does it get rid of them permanently during the uninstall?
I appreciate any and all input or recommendations from the staff.