I just installed the new Firefox 1.5 this morning, since SUSE put it up as an RPM package. I have used Firefox for quite awhile and I will say that 1.5 RC3 did not work with a lot of Java sites correctly, but I've just tried both Java (which didn't work right with RC3 as well as Flash and both are working perfectly here with SUSE 10.0. Actually an improvement over what I had with RC3. I uninstalled RC3 first, then installed 1.5, as suggested.
zenarcher