Odd login problem

[ghost ship in a storm]

Seem to have a strange little problem with logging into FG at the moment, when trying to log in from the front page I get a blank screen apart from the following message:

"In order to accept POST request originating from this domain, the admin must add this domain to the whitelist."

Mucking about with it I found I can log in by going to any post, clicking reply and entering username / password at that prompt - no problem whatsoever there.

Don't know if anyone else has come across this at all, couldn't find any similar posts. Poss something to do with my own setup? I'm using Millenium (I think I'm the only person on the planet who actually likes Win ME) with a machine that was top end when I bought it five or six years ago...

Many thanks, not a huge problem at all but just something that struck me as being a little odd...