It depends upon how you configured Avast and the components that you installed:
Avast's HTTPS Scanning interferes with Firefox and other programs - gHacks Tech News
However I don't believe that this is related to your problem as it occurs when using Linux.
I think you need a hardware expert. Moved house - something got dislodged or damaged during the move maybe?
Since this is happening on both OS's I believe it is not a Windows configuration issue. However, I can't be sure it is hardware either as LoL is working.
Did we try loading defaults in BIOS yet?
I don't think we have, because I have no clue how to do that.
Do you know how to open BIOS setup? It is written in the first screen you see when you start any PC. May be called "Setup" only, most likely a F-key or DEL.
Once inside, either in first screen or the exit menu. Once you load the defaults make sure to "Save the changes and Exit".
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