I have a four year old mac book pro. It has worked fine for years. I have always used firefox as my web browser. Since upgrading to firefox V4 I have had problems. Firefox freezes/ hangs every time I use it. IT seems to occur all the time, with only 2-3 tabs open and especially if i have something else open eg mail. I have been through the trouble shooting suggestions and done all that was suggested but it has made no difference. I use very few addons, only the decorative themes. Please Advise. Thanks