So I may have an infection; it's kind of hard to tell due to the behavior. I have been gradually updating Avast Pro on 35 computers since the newest version arrived. I had no problems at first, getting through most of the updates without event. However, on one laptop (Windows 7), I updated avast, rebooted, and, when I tried to start the program after reboot, I got an error: HTMLayout.dll missing, please reinstall the program. Thus, I uninstalled Avast, rebooted, downloaded the new installer, and installed; the active protection shields would not start, nor would the Avast service. I rebooted again, thinking it was required to make the program work. Now the laptop's keyboard and mouse do not work, not even in safe mode; however, the keyboard obviously does work in the BIOS (or I couldn't have gotten into safe mode in the first place). Luckily, the laptop is touch screen, so I am able to do some things. I have experienced a somewhat similar loss of keyboard/mouse functionality after installing Avast, but, in that case, the keyboard and mouse worked in safe mode. I am also experiencing some other strange behavior which I'm having a hard time explaining. When I tried to reinstall Avast after uninstalling in the first place, the installer I usually use (which is located on a network drive) would not work; it would get to the point where the screen displayed Avast with the wheel spinning, but it would never continue. Now that avast is installed, I cannot uninstall it from the control panel add/remove programs; when I click on it, the window appears asking if I want to uninstall/repair/update/etc., but if I choose uninstall, it simply does nothing.
Unless there's a better solution, I plan on wiping it and reinstalling Windows on Monday, but I figured I would ask the community first. Has anyone experienced similar issues? Does this sound like the result of a virus/rootkit? Or could it simply be caused by a corrupted Windows file wreaking havoc? The other time I had a keyboard and mouse stop working after installing Avast was caused by a corrupt Windows, and I ended up formatting and reinstalling. If it is an infection, I have absolutely nothing to go on as to where/what it might be; before this update, neither the nightly Avast nor the nightly Malwarebytes scans reported anything. Googling "HTMLayout.dll" reports that that file, itself, may be a virus. Does anyone know if this file is even really part of Avast? Any input would be greatly appreciated; I would rather not reformat, as this is kind of a mission critical system.
**EDIT** I opened device manager to see if the keyboard and mouse were simply disabled, and each had the following error: Windows cannot start this hardware because its configuration information (in the registry) is incomplete or damaged (Code 19). Furthermore, if I plug in an external USB keyboard it has the same error in device manager and will not work. The more I think about this, the more inclined I am to believe this is an infection; I'm not sure why else an Avast install would cause these particular drivers to become corrupt and no others (these are the only such errors in device manager). The logic of it just doesn't make sense to me unless I think about it like a strategic pointed attack.