Open PDF blocks Firefox 1.0.4

Dear all,

When opening a PDF document through a public web site Firefox 1.0.4 
(Mozilla/5.0 (Windows; U; Windows NT 5.0; en-GB; rv:1.7.8) 
Gecko/20050511 Firefox/1.0.4) will not respond until the document is 
downloaded and the appropriate plug-in is loaded. This will happen in 
both opening the PDF in the same window or in a new tab. When opening in 
"New Window..." the new window will not respond.

This happens on Windows 2000 Professional but not on Mac OS Tiger.

yfi
Bob