I think we might’ve had the same problem. This happened to me just now when I was using the Quadront mod, but I fixed it by upgraded SE4 gold with the patch. After that it worked. Go to their official site and download the patch, then upload it to your game's folder and everything should work out fine. If not, then one of these veteran players might offer better answers.
[ October 02, 2002, 03:44: Message edited by: bowzerdawg ]
Actually, I've discovered that SE4 itself sometimes, and the SE4 Launcher almost ALWAYS, has a hissy fit if I try to run it, and I have Eudora (my email client) running.
So I suggest turning off all nonessential applications, and THEN trying it.
If it then works, try it with each other application in turn, until you discover the cuplrit.
Then, never ever try to boot SE4Launcer with that application running.