I have a pac file that does a DNS lookup via dnsResolve, this hangs
firefox. I have checked the network dump and I can see the resultant
dns lookups and their successful reply, but still firefox hangs even
though it has the right answer. Any suggestions?

xulrunner-1.9.1.7 and firefox 3.5.7 via PPA, ubuntu jaunty

I haven't hacked js much so is there any suggestions on how I could
debug this?