TOAD 5.8 .
In the past I open a ticket in BETA session/forums of TOAD for this problem :
http://toadforsqlserver.com/thread.jspa?threadID=37594&tstart=45
The problem is the same.See my screenshot in attach.
I open TOAd I change to caramel theme, works with it and after one hour I try to return to default theme.
I obtain the exception.
I must kill TOAD process to close it.
Best regards.
Sergio Bertolotti