Firefox 3.5.5, which Mozilla posted for download late Thursday, fixes a small number of what the company called "stability issues" in the release notes that accompanied the update. Unlike almost all interim updates that Mozilla issues about once every six weeks, version 3.5.5 did not patch any security vulnerabilities.

The quashed Thursday was one that was causing a high number of crashes in the Windows version of Firefox 3.5.4, the update that to patch 16 flaws.

"We're seeing lots of crashes in the GIF decoder," noted Mozilla developer Joe Drew in the message that kicked off the discussion on Bugzilla, the company's bug and change tracking system. Only the Windows edition of Firefox 3.5.4 was crashing, others reported on Bugzilla. The GIF decoder is the component that parses .gif image files embedded in Web pages.

"This bug was actually caused by bug 514776 which removed the check for null mImageFrame," said another Firefox programmer, Jeff Mulzelaar, on Bugzilla. "I don't know why that check was removed." Information about the bug Mulzelaar mentioned is password-protected and not available to the general public.

Firefox 3.5.5 also fixes a stability bug in the Mac version, and another crash problem in the Windows and Mac editions.