The new version of the Firefox browser was downloaded over eight million times in its first 24 hours of release in what organisers claimed was a world record.
But the success was tempered by reports from a software security company that Firefox 3.0 contained a serious security flaw that potentially lets an attacker take over a PC if a user clicks on a booby-trapped link.
According to the Mozilla foundation that released the new browser, the software was downloaded 8.3 million times in its first 24 hours of release starting Tuesday morning.
The downloads were so popular that they initially crashed the servers running the operation.
At their busiest, the servers were handling more than 9,000 downloads per minute and within five hours had surpassed the initial daily download of 1.6 million set by Firefox 2.0 in October 2006.
DV Labs/Tipping Point did not release details of the security flaw except to Mozilla, but news of the glitch was damaging to the browser which was claimed to be much more secure than the previous version.
Firefox 3.0 offers faster web browsing than the previous versions, along with lower memory use and nifty features like a built-in search application that automatically combs your web history.
Tech critics greeted the new browser and recommended users to adopt it.
"Firefox 3 is the best Web browser I've ever seen. And I've been using the Web since before there were Web browsers," said ComputerWorld's Steven J. Vaughan-Nichols.
Firefox has been rapidly attracting users since its 2004 launch and now has approximately 18 percent of the market, compared to the 72 percent share enjoyed by Internet Explorer which has the advantage of being pre-installed on the vast majority of computers.
Firefox is mainly downloaded by individual users and as of February 2008 it had been downloaded over 500 million times. However, since one user may download the software several times, the best estimate for regular Firefox users is around 140 million.