Why does this happen? What can I do about it?

If I keep my posts short, no problem, but if I go several paragraphs, a little square pops up when I try to post. It wants my user name and pass word. If I type in one of my usual user names and one of my usual passwords, it just clears itself and keeps asking. So I hit cancel and it screams "Authorization Required!" in big, black, ugly letters and then it erases everything I have typed.

I am either too lazy or not smart enough to creat the post in Word, and then cut and paste it into RinkWorks.

Anybody know the cause? How can I recover my post? Does it help to throw the mouse at the monitor and kick the CPU?
Howard