Users are continuing to switch from Internet Explorer to Mozilla’s Firefox, making the imminent launch of IE7 even more vital for Microsoft.

Figures from web usage companies Net Applications and The Counter indicate that Explorer’s market share is continuing to tumble. Net Applications recorded a fall to 82.9 percent of the total market (compared to 84 percent the previous quarter), while Firefox’s share has risen from 10.7 percent to 11.9 percent in the same period. The Counter has also shown a rise from the previous quarter, albeit a slightly smaller one.

Most monitoring companies have reported a steady decline in Explorer's market share since Firefox was launched. The open-source browser has been increasing market share, thanks to security problems around Explorer. However, this year, researchers have found more security flaws - vulnerabilities that could herald a backlash against the browser.

Indeed, one web analytics company, OneStat, thinks that the tide is already turning. According to its figures, browser usage in the last quarter showed an increase for Explorer. However, OneStat could not explain the discrepancy: "We track our figures the same way that Net Applications does," the company said. The company didn't have an explanation as to why its figures differed so markedly from other companies' - although it did rule out one explanation. "Microsoft is not a client of ours," it said.