kmail and keyboard too slow - kubuntu 7.04

[Luca Ferrari]

Hi,
I've got just installed my new kubuntu 7.04 and it work great, but I'm 
experiencing a strange problem in kmail when editing a new message. After a 
while, or better after a lot of lines (about 50) of the new message editing, 
the keyboard (or the screen refresh) becomes very slow. I cannot see the 
digit I'm pressing on the keyboard for a few secs (even while writing this 
message). The computer is alive, and all the other processes are running 
normally. I can switch thru windows and desktops without any problem. Only 
the kmail composer seems to be very slow. For a new message it works 
normally. I've got no spellchek and I don't think the machine is too loaded, 
since I've got 1 GB of ram and the problem happens only while writing 
messages.

Any idea?

Thanks,
Luca