strange problem with IMP2.2.5

[Gérard Gachelin]

Hello,

We are using IMP 2.2.5 (platform : Sun Solaris8) since one year. 
Everything was working fine.
But this morning, we have a quite new problem :
Users can authenticate and log in.
But when they try to compose a new message, the compose window opens and 
closes immediately.
When they select a message in their inbox, IMP retrurns to the login 
page, without any error message.

Any idea ?
How to debug this problem ?

Thanks for any help.
-- 

-- 
Gerard Gachelin				Universite de la Reunion
15, Avenue Rene Cassin - BP 7151	97715 Saint-Denis MESSAG-CEDEX 9
Tel: 0262 93 82 72			Fax: 0262 93 82 60
Email : Gerard.Gachelin@univ-reunion.fr