Having updated to Firefox 4 I find it will open any webpage but refuses to open my webmail (with iinet). The error message reads as something to do with "no longer supported software" and that I should inform the relevant site. iinet.com.au have told me this must be an issue with Firefox as all other browsers have no problem. I have since removed FF4 andf gone back to 3.6.17. Once this is no longer supported I will have to return to IE8.