So i accidently tried to validate my copy of windows that i clearly knew was in no way legal and, surprise, surprise... It failed.
So for the past week, this annoying message appeared every time windows started up

along with this god-forsaken pop-up that appeared at random intervals, seemingly concerned that i "may" be a victim of software piracy.

No shit.
Enter one of the best and easiest programs i have come across for a long time:
Unlocker. A nifty little freeware program that lets you delete, rename or move any files that are in use at the time by any program or process, allowing you to bypass any sharing violations or inbuilt security settings that windows may have, displaying a list of processes that currently have the file locked so you can tell if it's a good (or bad) idea to do so.
So all i had to do was rename WgaLogon.dll in C:\WINDOWS\system32 to whatever and no more nagware. Bit of a band-aid solution, but i'm happy.