[TxMt] Coloured diff display?

[Kevin Horton]

I am trying TextMate on two machines, both PPC.  One machine displays  
subversion diffs with colours (the default behaviour, I believe), but  
the other has plain old black text with white background.  I am not  
aware of having made any selections that should have caused the  
difference in behaviour between the two machines.  I looked in the  
Preferences -> Fonts and Colors on the machine with no colours in the  
diffs, and I see nothing that appears to be related to diffs.  I  
moved ~/Library/Preferences/com.macromates.textmate.plist aside and  
started TextMate again, but the diffs are still monochrome.  Where  
else should I look?

TIA,

Kevin Horton
Ottawa, Canada