I've used Firefox for years - since at least 2003. I've used the Internet since before it was the world wide web - almost 20 years now. Now, I installed the Beta 4 for Firefox to test it - and I love it. However, within 48 hours of installing it, I had 2 viruses installed on my computer. I've never had a single virus in all the years I've used the Internet - NEVER until now. Since the websites I had open at the time were limited to Google News and an SSL'd site for my company payroll, I have no other option but to believe that F/F 4 allowed the virus through. I really hope I'm wrong, but I don't believe in coincidence. One reason I've always used F/F is that it doesn't normally allow this. It's not typically targeted by viruses and when it is, it's usually more secure than this. In the two days I had the Beta, I loved it. I want to see it succeed but this is a critical failure. The virus even got past my up-t0-date Macafee software (another issue entirely). Please look into this and make sure that the Beta doesn't expose computers. Unfortunately, I can't even tell you which virus files were allowed through. My computer is currently at the IT office being wiped because after two days of trying to clean it, we can't remove the virus files. They have infected all of my browsers - and I use 4 different browsers. Thanks.