So, at the moment I have only found one more mac user (yo Marko vote for the bug dude) that has experienced the same problem with me. After long hours using Firefox 3 at some point the browser refuses to open new url's either in tabs or new windows! Eventually in order to become usable you have to kill the process and restart!I have filled a bug in the Bugzilla service of Firefox, if you happen to have similar probs from times to times, please vote! Eventually I tried to search for similar bugs just to avoid filling a duplicate but I could fnot ind anything relevant , maybe there is one! I consider this a huge bug - its not blocking since it happens randomly but it has to be resolved at some point - hopefully- please firefox developers!