Okay, so recently (within the hour of this post) a yellow, one-pixel vertical strip has appeared on my monitor. Here's a picture:

(click for full size)
Now, this yellow strip goes over anything else, cursor, windows, everything. And what's stranger, it doesn't appear in screenshots, here's a screenshot of my desktop in the same place:

(again click for full size)
Obviously, no yellow line.
I think it might be a problem with my monitor, but I have no idea what could've caused it. Is there any explanation for what's happening, and how can I fix it?