Can anyone help please? Still doing it, did another system restore, this time going backa week, emails returned to normal for 2 minutes then back to blank again. Arrggghhh

How is that related to Firefox? Firefox doesn't do email, it's strictly a web browser.

If you are using Firefox to access your mail, you are using "web-mail". You need to seek support from your service provider or a forum for that service.

If your problem is with Mozilla Thunderbird, see this forum for support. http://www.mozillamessaging.com/en-US/support/
or this one
http://forums.mozillazine.org/viewforum.php?f=39

Hi, I can open my email in internet explorer and works fine but when I open in MF I can't see anything, so presuming its a MF issue? Have checked with Sky, my provider, and all is fine, and as I can open in another browser nowt they can do. Surely it has to be something in MF or else it wouldn't work in IE?

Disable adblocker as this was happening to me with my virgin email account (google in all but name) and when i disabled it all my emails were visible again! I've now disabled all my add ons just to be sure i don't get a similar issue in the future, perhaps a little of an over reaction but better to be safe than sorry. Hope this solves your issue.

Justabod - thank you!!!! It worked, can not thank you enough Nicki

No worries Nicki just happy to help you, i know just how frustrating the issue was as i was on the receiving end myself and it took ages for me to work out what was wrong. The issue is related to AdBlocker Pro since Firefox 8.0 went live, no idea what is causing this though.