Outlook/office dialog boxes look funny.

For some reason, one of my (terminal) servers has started to show funky dialog boxes in office applications. Everything looks plain, like in vb3 days and the options dialog box in outlook is unusable as the dialog is too small for the content. Any ideas on what has caused this?
Wrong dialog box

Correct Dialog box – everything fits in the screen (although I snipped the bottom off)

Update – Mike – you are a genius. The funny thing is that I thought it was the fonts but at first glance it seemed ok. However, I compared the fonts in the appearance setting of the display applet in control panel and sure enough, the font settings were blank. A look at the Tahoma font in the font applet and it was 0 bytes – aha! Installed Tahoma again across the network and the fonts and dialog boxes are now back to normal. – Sir, I owe you a pint.