This list covers some of the known problems with Firefox 3. Please read this before reporting any new bugs.

All Systems

        * Installing Firefox 2 in the same directory in which Firefox 3 has been installed may result in Firefox 2 being unstable (bug 423226)
        * If Flash content is active when Firefox crashes, the Crash Reporter may not activate (bug 422308)
        * Deleting an entry from the history sidebar, then invoking the Clear Private Data tool can result Firefox crashing (bug 426275)
        * The IME input tool used to enter Japanese, Korean, Chinese and Indic characters is covered by the "Add Bookmark" panel. Users can use IME for input in the Library window by selecting "Organize Bookmarks..." from the Bookmarks menu (bug 433340)
        * Some add-ons that depend on deprecated code may not install properly (see bug 406807)
        * Privacy > History > Remember visited pages to "0" has no effect (bug 366075)
        * Some users who have customized toolbars may need to reset them if they are missing the Back and Forward buttons (bug 426026)
        * Some Web pages (such as mlb.com) do not properly detect if Silverlight is installed and will not function properly (bug 432371)
        * The DOM Inspector has been removed and is now available as an add-on.
        * Support for Cross-Site XmlHttpRequest has been removed until the specification becomes more stable and the security model is improved (bug 424923)
        * After dismissing the "Do you want Firefox to remember this password" prompt, it is sometimes not possible to focus form fields unless you reload the page (bug 433942)
        * The new Location Bar, Add Bookmark dialog, and Download Manager information popup behave inconsistently with Window-Eyes. JAWS 8.0 or better is recommended for this release candidate. (bug 393398)

Microsoft Windows

        * A Windows Media Player (WMP) plugin is not provided with Windows Vista and some other versions of Windows. To view Windows Media content, you must install this plugin by following these instructions. After installing you may need to check for Windows Updates before the plugin will show content properly.

Mac OS X

        * Japanese, Korean, Chinese and Indic characters can not be entered (using IME) into text fields in Flash objects (bug 357670)
        * If you are using IPv6 from a network location that doesn't support IPv6 routing your DNS lookups may be very slow. Set network.dns.disableIPv6 to true as a workaround (bug 417689)
        * Items in the "File" menu show as inactive after using the "Print" item from that menu - switching to a new tab restores them (bug 425844)

Linux and Unix

        * Users on a PPP connection (dialup or DSL) may find that Firefox always starts in "Offline" mode. Toggle File > Work Offline as a work around (bug 424626)
        * Users running Ubuntu 7.10 may need to update their certificate databases in order to submit crash reports (bug 407748 for instructions)
        * The mouse button assignments for Back and Forward have changed, users may need to reconfigure their pointing devices (bug 420294)
        * Incompatibilities between NVIDIA drivers and some versions of the X server cause scaled images to render incorrectly (bug 411831)
        * The Orca screen reading software does not read some text, such as the save password notification, site identity information, or the default prompt text in search fields - these are known problems with Orca (see Gnome bug 533109 and 533125)