I don't know if I can get advises here but I'll give it a try. I searched for resolving this issue on may forums to no avail :
I have XP SP3 with Firefox 4 and, yes a dial-up modem that was autoconnecting couple of months ago and, out of the blue, it stoped autoconnecting for... I don't know why ! I don't remember if I installed something that interfered with this feature, or if I changed something in about:config of Firefox. I tried to search some regitry keys that would explain this behavior to no avail. Or I have'nt checked the right keys.
So I say again : evrything else does autoconnect so, it is not the registry keys related to EnableAutodial or AutoConnect that are the culprits here.
Any ideas somebody ?