I've created account just to confirm there is a problem with Win8.1 Pro 32bit and Avast Free Antivirus 22.4.6011 (build 22.4.7175), also problem exist on the latest Avast Free Antivirus 22.5.6015 (build 22.5.7263). So far total of 6 computers with issues here, not mine but computers from people I know.
As OP already mentioned after updating to Avast Free Antivirus 22.4.6011 (build 22.4.7175) in most cases Windows freezes either while loging (with user account pic shown) or right after displaying desktop.
Saw this issue on Win8.1 Pro 32bit first time on one desktop PC on May 23, 2nd case on May 24, 3rd May 25, 4th case on May 28, 5th case on May 29 on my wifes brother PC... All of these PCs were facing issues after updating from Avast Free Antivirus 22.3.6008 (build 22.3.7108) to Avast Free Antivirus 22.4.6011 (build 22.4.7175).
6th case... Yesterday friend of mine called about some issues he has with his laser printer, got the access to his computer via TeamViewer and so he also uses Win8.1 Pro 32bit on his old laptop, also using Avast Free: Avast Free Antivirus 22.3.6008 (build 22.3.7108) ...so I've asked him if I can try something (to update to the latest Avast 22.5.6015), he let me to it, after update process Avast asked to restart Windows but after restart Windows hangs while loging, right after showing desktop.
On all above PCs had to boot Windows into Safe Mode, then wiped Avast using Avast Clear 22.5.7263, after that Win8.1 Pro 32bit booted without problem. As a workaround, so that they have some kind of anti-virus protestion, on all these PCs I've installed Kaspersky Free.