Can I just say a 'BIG THANKS" to OLDCRAZYLEGS.....
I have been trying to get firefox 2.0 to respond to javascript "BACK" button, for 1/2 a day now.
All solutions worked fine in IE7...but none worked in FF2.0.
The screen would momentarily flicker back to the previous page, and then land back on the one that made the call.
I used 'window.location = history.go(-1);'
.... and placed this within a function in the head of the page (returnto lastpage()

, and called that function from the html doc via the <a href="#" onclick = "returntolastpage();"> pic to click </a> method.
This worked fine in IE, but not in FF. I tried all manner of permatations, but with the same result.
However this embedded 'inline' method of OLDCRAZYLEGS works in both browsers, and has saved me some grief! .... many thanks guys.