Mozilla are advising Firefox users to disable McAfee's ScriptScan software, saying that it could cause "stability or security problems."

ScriptScan ships with McAfee's VirusScan antivirus program. It's designed to keep web surfers safe by scanning for any malicious scripting code that might be running in the browser. But according to Mozilla it has an unintended side effect: it can cause Firefox to crash... a lot.

In a note posted to its website, Mozilla said that the add-on "causes a high volume of crashes," and is "strongly encouraging" users to disable the software. The warning applies to all users of version 14.4.0 and below of the plugin, Mozilla said.

The Firefox browser started popping up warning messages earlier this week, advising that users disable the software

In McAfee user forums, there is a smattering of complaints about the Firefox problem.

The problem affects Firefox 7 users, according to Francie Coulter, a McAfee spokeswoman. She said: "McAfee has identified the cause and is working actively with the Firefox team to resolve this issue and expects to roll out an update shortly."