Sorry, there is no setting for that in Firefox. You need to change it in Windows. This article is a bit "dated"and it applies to WinXP. See if it helps you, or search for a newer article for Vista.

http://drewthaler.blogspot.com/2005/09/changing-dns-query-timeout-in-windows.html

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DNSQueryTimeouts Multi String: "1 2 2 4 8 0" -> "4 8 8 16 32 0"

Thanks for the reply, it seemed very promising. However, once accomplished, it didn't seem to affect the timeout period, even when the numbers were made much larger. My guess is that the timeout is being controlled by my router, unless this registry entry simply doesn't work for Vista. I will let you know if I find new info.

I've just encountered this problem with FF4. Doesn't happen with FF3.6.16 nor IE8. It happens when redirected from a secure payments page to a 'verified by visa' page. The error message pops up.

This issue appears under two different Mozzila "Questions". Both appear to have the same OUTDATED, INEFFECTIVE ANSWERS. A lot of us are on WIN7 now and still have erratic network speeds due to cable multiplexing -- but have been trained to leave the registry alone. Has not anyone solved this problem -- other than going notoriously unreliable FIOS ??