I seem to have had a nasty in my computer. AVG found it, said it couldn't correct it but not in a real dramatic way, just did its normal scan and went about its business. I had first noticed something screwy after Thunderbird had downloaded and installed an update, I got dialog boxes wanting email address and password when I tried to send mail or post to usenet. I had already seen the trash in sejw and figured maybe someone had a new trick that I hadn't seen yet.
For whatever reason, I felt suspicious of a mature program asking for basic information after an update and stopped using it while I looked into it. Didn't really find anything, googled pretty well but not a lot of luck, but when I realized the AVG wasn't getting rid of what it said was bad and manually deleted it I'm no longer seeing a dialog box when I try to post with this machine.
The downloader was in my Mozilla app, down in firefox\profiles and simply deleting it seems to have solved the issue.
We'll see anyway..
John