System Fonts Buggered?

[The_Unnamed]

For some reason a bunch of my system fonts have gone all funky.



The seem to all be bold and not the standard font.
I have check in appearances and all fonts are set to Segoe UI, Pt9, No Bold.

The problem also seems to be when browsing websites (Such as MyBB) all the posts are in the same font.

Any idea what could have caused this? I can't recall installing anything dodgy recently.

 

[The_Unnamed]

Sorted out the problem.
For some reason the Tahoma font was not installed on my PC.