Mozilla + Enigmail signature problem

Hi Newsgroup,

I have a very annoying problem. I use Mozilla 1.7.2 under FreeBSD 4.9R 
for mail and news. I have Enigmail installed which I use to GnuPG sign 
my outgoing e-mails.
Lately I found that several times there is a problem with the signature.
When I send the mail, it asks for my password. Giving the wrong password 
results in an error message and the mail does not leave. This is fine.
Giving the correct password the signature is generated and the mail 
leaves. This is fine too.
Then, if I go to my *Sent* mailfolder and click on the mail I just 
signed-sent, Mozilla says: Bad Signature from Keve Nagy.

I tried to send some test mails to different addresses (my company, my 
family, my school address, etc) to see if a certain address/domain is 
related to the problem or something else.
Most of my test e-mails (very short ones) appear fine in my Sent folder, 
saying: Good signature from Keve Nagy.
Still, lately more and more of my e-mails seems to show up in my sent 
folder stating it has a Bad signature. Although, there is no error 
message when I send them.
I always use the same signature.

Is there anybody else experiencing similar problems?
Any idea how to track where the problem might be?

Thanks,

Keve

-- 
If you need to reply directly:
keve(at)mail(dot)poliod(dot)hu