My husband (Mr. "Hey, honey! I learned trigonometry this afternoon!") does web design and programming, and he has to test on all the major browsers to make sure things run smoothly. The most trouble he has is with Explorer. Everything will run smoothly on Firefox, Opera, Chrome, Safari...and then crash on Explorer. Not a day goes by without Hubs screaming at Explorer for not recognising something simple in a CSS code -- or PHP, or SQL. It's actually humourous to hear some of his name calling, but I digress.
Got with Firefox. Or Chrome. I use Chrome for stuff like Facebook, and Firefox for programming. Hubs won't touch Chrome (other than to test) but I like it for its clean, maximised screen.
And for security -- Firefox is better for security. Chrome seems to be doing rather well in the security as well, especially since it doesn't have nearly the add-ons that Firefox has.
All this talk about Explorer makes me suddenly miss my iBook.