Display settings in Windows "blocky" / "pixelated"

I was recently playing a video game late at night, and my anti-virus
came on. It switched me to the windows desktop, but bcs I was still
playing the game, I switchedback immediately using ALT_TAB.

When I exited the game, I noticed that my fonts are not smooth, but
rather "blocky" or "pixelated". My entire environment is like this, no
matter the application.

I have changed resolutions, color depth, and unchecking, then
re-checking smooth screen fonts. I have tried cleartype, I have tried
dpi changes.

I have uninstalled the video drivers, reinstalled both the original
drivers that came with the card, and downloaded/installed the newest
drivers for my GeForce FX 5200. These do not make any difference.

I have tried an sfc /scannow to no effect.

What might be the cause?

-Delly