Thunderbird spell check

[SteVe Cook]

Following power failure (after the cat picked a fight with the mains 
cable) one of my 3 thunderbird profiles seems to think every word I type 
in is spelt wrong.  I've got 'check spelling before sending' selected 
and when I send an email it picks out every word and offers the same 
word as a correction, if a word is spelt wrong it does supply the 
correct spelling.  Any ideas as to what's happening and how to correct 
it.  I've searched the net but can't find any body else with this problem.

Thunderbird 1.5.0.7
Dapper 6.06.01 LTS


SteVe