Security vendor Zone Labs, which produces the software, is facing criticism on its own and other public forums -- such as those provided by large Internet providers -- about the problems, which seem to affect version 5.5 and above of the firewall. The initial 5.5 upgrade was made available in November last year and has been updated several times since.
The primary issue for users appears to be an inconsistent Internet connection, with some users reporting the firewall temporarily stopped all Web browsing or e-mail access only to re-enable it seconds later. Others have claimed their broadband Internet speed has been severely reduced.
"For the past few weeks my download speed has been cut in half," wrote one agitated user on Zone Labs' forums. He said he had uninstalled the software and regained full-speed access, only to install it again and be cut back down to half-speed. This problem has been reported multiple times on broadband user sites like Broadband Reports in the United States, and Australia's own Whirlpool.
Users claim by re-installing a previous version of the firewall they were able to regain a full-speed connection. However, this could leave them open to vulnerabilities inherent in previous versions of Zone Alarm.
While a spokesperson from Check Point Software Technologies, which owns Zone Labs, told ZDNet Australia  he would investigate further although he was unaware of any issues this morning. But at least one reliable source acknowledges the problem exists.
In a posting by 'Iggy', he acknowledged the existence of many frustrated users but said he personally didn't encounter such problems. He suspected the disruption could stem from the way certain PCs were set up, or that ZoneAlarm conflicts with certain software being used.
"There has to be some sort of conflict somewhere," he wrote. "This has to be something [some] other users are running that others don't."