I 'wiped out' my mod collection on this computer (hereby known as Computer A), meaning that I have relocated it entirely to another, brand new computer (computer B). Before the update, I never had problems with HL1 on steam. However, after this update, Computer A crashes with a Blue Screen, and HL1 and all mods do not work as described in the journal entry. Then I relocate everything to the brand new computer (Computer B), and, under the same circumstances, crashes with the Blue Screen. --> This is a brand new comp, mind you, so there is no other reason for it to have a blue screen.
Valve has in the past released unstable updates on steam. I'm just hoping that this will be fixed ASAP.