Firefox asks erroneously to download and install flashplayer

(https://secure.dexia-bil.lu/ssl/logon_flash.asp?lang=en). If I go to the last page directly it is displayed correctly. Flash player is installed and works fine. 

When I connect to the site of my bank (http://www.dexia-bil.lu/webquotes/index1.asp?h=1&lang=en&menu=onl&href=htm/acces_client_lu.asp?lang=en) and click on it shows the page (https://secure.dexia-bil.lu/ssl/logon.asp?lang=en) instead of (https://secure.dexia-bil.lu/ssl/logon_flash.asp?lang=en). If I go to the last page directly it is displayed correctly. Flash player is installed and works fine. Strange enough I have not this problem with the Epiphany webbrowser. I am using ubuntu 10.04 64bits, Firefox 3.63 with Shockwave flash 10.1 r53 == This happened == Every time Firefox opened == I try to login into my banks website == == User Agent == Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)