Spell check error in OWA 2003

Have OWA on Exchange 2003, getting the following error UNLESS we logon
with domain\username:

The spelling in this item can't be checked. Try again
later.

It also appears to "time you out" so you have to log back on again if
you attempt to do a spell check.

Tried the following KB articles, and still no go.

http://support.microsoft.com/kb/820378
http://support.microsoft.com/default...b;EN-US;825430

Our OWA is behind an ISA 2004 server (reverse proxy).

Any ideas?

[nicbrown]

I was wondering if you have come across a fix for this issue yet. I was just notified that we are experiencing the same problem. The odd thing is, some of our systems work and others do not.