Can anyone still see a 5cm blank space at the top of the pages?

After scouring the phpBB forums looking for the most unlikely thing it turned out the viewtopic.php had a carriage return at the end of the file. I removed it, re-uploaded it to the site and presto problem solved.

For all you php fans out there. I think this is probably due to developing on Win32 and then having the site run on Linux/Unix.

If you notice anything else curious, let me know.