The updates will take Firefox and Thunderbird to version 1.0.6, while the Mozilla Suite will be updated to version 1.7.10, wrote representatives from the Mozilla Foundation on the group's developer news blog. Mozilla oversees the software's development.
It appears security fixes incaused the problems.
"There is a very real chance that some of the general security improvements in last week's 1.0.5 update may impact a number of extensions that worked with 1.0.4 and earlier, and we want to identify and address as many of these as possible before we release 1.0.6," the representatives said.
Because of the impending update, the Mozilla Foundation has asked developers to temporarily halt work on localizing the software for non-English language markets, a move that has drawn criticism from some adherents.
"We are getting lots of e-mails from Firefox users in Poland asking us about why isn't Firefox 1.0.5 available in Polish," wrote one developer in the localization newsgroup.
"A few days more, and it's gonna be a big public relations disaster for Firefox outside the U.S.A.," the developer added.
Another developer attacked the foundation in its bug-reporting forum.
"Tens of millions of users are still using 1.0.4 while critical security bugs are already published after en-US (U.S. English) 1.0.5 release," the developer wrote.
Calling for the foundation to release its software in all supported languages simultaneously, the developer said that by delaying the foreign language versions, Mozilla was wasting the work done by developers promoting the foundation's brands in local markets.
Test versions of the updated software are available, and the foundation has asked third-party developers to make sure their extensions work.
"Extensions that interact with Web content and events may be the most susceptible to these changes," the foundation representatives wrote. "Mail-handling extensions such as (secure e-mail extension) Enigmail for Thunderbird and the Mozilla Suite should also be tested heavily."
A Mozilla Foundation representative was not immediately available to comment on the changes.
Renai LeMay of ZDNet Australia reported from Sydney.