No (Blank) subject when replying to emails

[Mohamed Hussein]

Hello,

I am getting this very annoying (seems random) problem, sometimes when
I reply to emails or send new email, my mail is sent with no subject.

I am definitly sure that I am not carzy, and that I have written a
subject, also this happens with replys, so for sure there is a subject.

This has been very VERY annoying, does any one know the cause of this
problem.

I am using O2003, with Exchange Server 2003. I am running on Win2k.

Thanks in advance.