I uninstalled MSN Messenger Plus.
Same PB...Sorry... It seems not to be Messenger Plus.
For information...looking further...the problem occur only when i clic on one of my personnal images in the background Images list (kind of MRU)...something must be wrong with them...
My mistake (cause it occured as soon after i installed Msn Messenger Plus!  Bad coincidence...)
Sorry again 
Ziad O'Hanlon