Hi beregond
I have seen this problem in the distant past and think it was basically an out-of-memory error caused by experimenting with cups and generating a large non-printing print queue. I think the only solution is to move cups daemon from the Computer -> Startup folder (move it into Computer) and reboot then check that Seamonkey starts.
If that is successful you will then need to clear the cups print queue.
With Seamonkey running doubleclick cups daemon to start cups.
Point Seamonkey to cups admin gui at
http://localhost:631Click on the Printers tab
Click on your printer
In the Maintenance dropdown box select Cancel All Jobs
In the Administration dropdown box select Modify printer to check the printer settings are correct
Move cups daemon back into the Startup folder
Hope the above is of help
Pete