Well, only problems I've had with the combination setiqueue / firedaemon-seti-service getting new wu is:
1; if running setiqueue on NT4 there after re-boot the setiq-service times out so must manually start it.
2; if using Computername as proxy-setting & haven't got a network-card... Use 127.0.0.1 instead.
3; if using dial-up, the computer wants to dial out instead of contacting the setiqueue running on the same machine... Fixed by running service as an user that don't have a configured dial-up-setting...
Uhm, and unplugged network-cable, or the queue-machine is down.
The only other problem can think of for the moment is if the ip-address has changed...
Defective wu? Setiqueue checks & deletes corrupted wu then downloading or before delivering to a client... So if you haven't got a machine-crash or disk-problem the wu shouldn't be corrupted... Of course some 1-minute-wu shows up, but this is another problem.
If the seti-exe is corrupted, 1st to look for would be virus, 2nd disk-corruption...