Ok.. so... for a little while now, any video I watch on my computer has the audio out of sync (you know, watching someone get punched 2-3 seconds before HEARING the punch...). And now videos are a bit choppy/skippy, which sometimes reduces the out of sync, sometimes increases it. And this is for ALL videos, whether streaming (on any site) or watching a DVD (and I tried various players).
I've also had A LOT of blue screens and in an attempt to help fix those, a tecchy friend of mine suggested I try updating motherboard and other drivers. Now, this model of motherboard is discontinued and so most recent drivers date back to 2011 on the ASUS website... and I don't really dare installing more recent ones I found on other sites, unless someone tells me, sure, it fits, go ahead. So, updated a few drivers (got the latest audio driver, graphics card driver), updated Flash Player and Java. Tried turning on and off hardware acceleration.
Now, as for the bluescreens, said friend reviewed some debug files I sent him, which all pointed to a Kaspersky driver being faulty. To test if it's the AV software itself being faulty or some error on the disk that Kaspersky points to, I've uninstalled Kaspersky and got another AV software (AVG). Been a couple days now... we'll see how it goes!
Over the weekend, I've noticed the graphics card temperatures spiking to 90C from 65C in less than 2 minutes while being idle in NWN. So, shut it all down, unplugged the machine, opened it and did a thorough dusting. Now temperatures are smooth and stable between 60-65C at all times! (yay!)
..... but. Videos are still choppy and audio is still out of sync. And I'm running out of ideas, short of formatting and reinstalling Windows, which I'd like to consider as a last resort.

I've searched the Web, did some checking following tips from forums. One of them (this post) said he looked in the registry and deleted some Master/Slave files and that did it, but not sure I want to play in there without being sure it won't completely screw up my machine (in which case, my last resort solution would likely be my only solution!).
Virus scan comes up clean.
Defrag is good.
Scandisk is good.
Also of note, maybe -- the same streamed video skips and is choppy like nothing else on Chrome and Firefox... but near half way through (when I stopped as it was late), it went smoothly on IE. *scratches head*
Now that confuses me to no end.
So. Thoughts? Ideas? Cookies?