Mozilla is struggling to get the third, and probably final, beta of Firefox 3.1 out the door, which means its first quarter release target is looking increasingly doubtful.

"At this time, we don't have a good estimate for when we'll be done," said Mozilla. “Many of the bugs are proving to be tricky and complicated to fully resolve."

The corporation up to now has said it would deliver Firefox 3.1 in Q1, however, following a series of bugs in the browser including problems with its new JavaScript engine, Mozilla is suddenly being shy about release dates.

Earlier this month the open source outfit pushed back Firefox 3.1’s third beta release by a week to allow the firm to fix some bugs in the browser. It set a new date of 2 February for when the browser would land to allow it time to fix some glitches in the surfing tool.

However, Mozilla has now backed away from announcing any definitive release dates, which is hardly surprising given that it keeps missing Firefox 3.1 internal deadlines for what appears to be an increasingly challenging browser release.

Developers are still trying to patch 18 show-stopping bugs in Firefox 3.1, said Mozilla, 15 of which are located in its TraceMonkey JavaScript engine.

TraceMonkey is a key selling point component for the corporation because it renders twice as fast as previous JavaScript engines used in older versions of the Firefox browser.

But until those major glitches are nullified, Mozilla can’t confidently offer a release date for Firefox 3.1.

That’s a fact that could spell bad news for the corporation, especially given that Microsoft’s upcoming release of Internet Explorer 8 is possiblymaybe imminent. ®