Left with no other option, I tried unstalling the game and discovered that that function also no longer worked. In order to still remove the game, I did it manually through a tutorial and then went about installing it again after defragmenting my drive.
Installing the base game went like a dream, but when trying to install University this happened: http://i34.tinypic.com/hskxtz.jpg
The same happened with Nightlife, H&M Fashion Stuff and Celebration Stuff. Not only that, but the game will not start. Not even after a fresh re-install and no alterations to the game file itself. I am well and truly stumped. Can someone help me on this one? It's not gone beyond just wanting to play the sims. It's a matter of pride!

My system specifications:
AMD Sempron Processor LE-1250 (2.2 GHz)
2,0 GB RAM
NVIDIA GeForce 8600 GT
Windows XP