How to reset website "Browse" box?

When I click on "Browse" to upload a file to a site or click > File > open in any program (firefox/word) I get a small box which shows the files I can open/upload etc. Lately I've been having issues with this "browse" box, is there a plist I can delete to reset it, I've tried removing the finder plist but that hasn't helped.

Hope that makes sense!

 

The box wont re size, only displays two rows of files due to the re size issue, will only let me scroll part way down, crashes, have to double click on some of the boxes........then crashes.

What a pain, any idea which plist to delete or how to reset, this is the only issue I have so I suspect something (such as a plist) has become corrupt