Major bump here I know, but one day Firefox updated itself without asking me. My favorite theme, Gradient iCool, doesn't work after 3. And lately, in Windows 7, it gets extremely laggy when I have more than a few tabs open... as in, click a link and nothing happens for a few seconds, or type and nothing shows up for several seconds at a time. Fine in IE, and fine with FF in Ubuntu. I have 8 GB (though the Windows side is 32-bit) and things run well in general so I blame FF. AVG always tells me FF is using a high amount of memory (in the 700s MB when it notifies).