The roadmap called for the sixth Firefox beta to freeze the browser's new features so that developers could work on making them stable, but that plan's been pushed back to the seventh Firefox beta as Mozilla hustled out some quick fixes for the browser. Available for Windows, Mac, and Linux, Firefox 4 beta 6 fixes a a critical stability bug affecting all platforms and a major bug related to plug-ins on Macs.

The stability bug at issue was first reported on August 20th, and remained the top-reported crash-causing bug on Windows versions of Firefox 4 beta 5, with 9399 crashes. The Mac bug messed with plugins, showing white boxes over some Web sites while making it challenging for users to type into others. Mozilla's Firefox 4 beta 6 changelog also includes a full list of changes made to the beta.

Mozilla hopes that the next Firefox beta, now beta 7, will stick to the Firefox 4 beta 6's old schedule and be released by the end of September.