Try disabling the ZoneAlarm Toolbar extension or see if ZoneAlarm has its' own pop-up blocker.

I do not believe Zonealarm has a popup blocker. I have been exploring Zonealarm screens seeking pop up blocker info but have found only references to "Pop up alerts" generated by ZoneAlarm as it protects. By "disabling the Zonealarm toolbar extension", do you mean un-checking Zonealarm toolbar in the Firefox [View-Toolbars] pull down menu? TIA, stu

No, that would involve to disable that extension in Tools > Add-ons > Extensions

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Go to Tools, Options, Content, in Content clip off Block Pop up Windows or click on Exceptions and put in your favorite web addresses. Then go to Advanced tab and click off "Warn me when web sites try to redirect or reload the page".

If you have Zone alarm try disabling it in tools->addons

I develop a program its been working well until my client installed zone alarm, so what I did is disabled its addon installed in firefox after that; the popup screen came out after i restarted the browser...

Just my two cents hope it helps...