Sorry, I meant extensions. I don't have any plugins at all. I know what you mean about some causing problems, certainly one called FastestFox has been implicated, but, I eliminated that from the equation and it still happens.
What is also peculiar is when I try changing the search text even by only one letter, at least 3 or 4 popups come up asking to down load the file, so, the problem doeasn't seem to be related to the number of charactors changed/added to the search pane.
For completeness I'll try to upload a screen shot of the messaage box