with mozilla 1.7.5 composer including images in Mozilla Mail signature doesn't work

Hallo!

Using the composer of mozilla 1.7.5  I tried to include a jpg-logo below 
my adress in the signature of my mozilla Mail business account. There 
was always shown the frame with the cracked image symbol. And during 
sending  a mail with this signature there was a failure message saying, 
that there was an error with creating an attachment. But my mail haven't 
had an attachment.

Can anyone help?


Thanks in advance

Patrick