Spyware and viruses will make your computer run slow and crash they wont give you artifacts on screen.
You should really know this because of all the stuff you went through with your graphics card. Like people have said artifacts normally come because of a graphics card problem, overheating or it's just broked and maybe even a software problem (graphics card drivers) but that's if you're lucky.
If you are having the same problems as cebesius, clean out the dust and see. If that doesn't work then you know the other things it could be, which no one here can help you with.
I also had a minor graphical glitch, which I don't think I ever had before patch X4 (see attached pic). Only happened once after installing x4 and starting a new online game. I wasn't able to reproduce it, so maybe it's nothing, but since other people reported graphical errors, I figured it couldn't hurt to post it (maybe it's related to the PlateHandle-thingy?).
Linsen, I also noticed the same thing tonight when racing at Westhill in the LX4. I've not noticed this bug before, but then again I don't really drive LX4 much anyway...
I can't seem to reproduce this, the replay seems to loop as usual with the options menu open.
I've tried a replay started from in game (by pressing '1') and then pressing SHIFT+O to bring up options then waiting until the end, and I've tried the same from the replay menu screen.
Can you give any more info, like which kind of replay you are watching, hotlap, race, qualifying, if results need to appear first, which options screen are you in, etc... it sounds like a quite serious bug (hangs and crashes are always high priority) but i just can't reproduce it.
This has never happened to me before and I've never heard of anything like it, so I don't know for sure if it's caused by patch X or not.
The only thing I did out of the ordinary was hold the clutch before the race restarted.