Release notes state that this update contains the following enhancements:
* Improvements to product stability
* Added changes for Frisian locale (fy-NL)
* Several security fixes
mozilla.org also offers the following notes about potential problems with extensions and themes after applying this update:
* If after you run the Firefox 1.5.0.5 installer, the extension compatibility and update wizard does not appear, go to the Extension Manager and manually check for updates.
* If the Extension Compatibility and Update wizard downloads and installs extension updates but those updates are not applied, open the Extension Manager and manually check for updates.
* On Intel-based Macintosh computers, PowerPC-only binary extensions do not work unless users upgrade to an Intel-native or Universal version or turn on Rosetta. To turn on Rosetta, click on the Firefox icon, click “Get Info” and then check the “Run Under Rosetta” box.
The new release is available as a 16.1 MB standalone download.