I am in trouble with PM replying

I dont know what's happening: I cannot reply to a PM I received.
I go through the usual moves ,I log in fine,open cp,see messages,open the message I want to reply to,I copy-paste the text I wrote in OpenOffice3,.odt format, but when I press the submit button I am notified of a

same fate if I press Preview.

I thought it might be something with that particular OpenOffice file,so I used a Wordpad one, to no avail.
Amidst these 7-8 attempts I succeeded in sending a short text written on the spot.
It's not the recently installed KeyScrambler in Firefox because I tried two or three other sites where I have to give a password and press a submit button and they do work.

If you and I will see this text posted after I press submit it will mean something is wrong with copy-paste, or with .odt text,I wonder why.
It means I will have to manually write everything in messages.

Anyone can help?