This may be relevant to the discussion. We are having problems at work with site access using Firefox, as opposed to IE (what is happening with a particular part of our site is that it displays lists of items and under Firefox the lists are overlapping, this does not occur under IE). The techs have come up with this.
'Our Web pages are designed to be consistent with the xhtml1-strict DTD, as declared in the DOCTYPE header. Firefox and Netscape do their best to respect the strict HTML standard, though IE doesn't care much about that.
The header is included from files provided by us. These actually don't follow the strict HTML standard. Therfore, they are not displayed properly on Firefox/Netscape.
From the company portal, I could see that most pages support the transitional HTML standard, which instructs the browser to support HTML as well as XHTML, as much as it can do.'
Could well depend on the doctype used in the Pprune site.
(Edited to add. I use Firefox and have the small window problem as well. There are also problems with scrolling when replying to a thread - the scroll wheel on the mouse doesn't work and I have to use the cursor bars for positioning).