On 25 Jul 2007, at 15:01, Kevin Horton wrote:

there is still a puzzling difference in behaviour between the two machines. On one machine, diffs are automatically detected as language Diff. On the other machine, they come up as language Plain Text.

How are you getting the diffs into TM? The language is associated with the file extension, so if you changed a .diff file to Diff it should now be stored that way