Iphone 3g Restore failure Itunes reads no sim card installed

Ok, where do I start, First off hello to everyone and thank you for any support you can give me.

Equipment:Iphone 3GS
Firmware: 4.3.3
Jailbroken: Not Currently, has been in the Past
Unlock: Never
Problem: My father tried restoring his phone dont ask At&t told him to do so. After restoring the phone it is stuck at the Itune logo USB cable page that allows the phone to make emergency calls, and the phone occationally reboots, After the restoring the Iphone Itunes says No Sim Card Installed. I have tried a known good Sim Card it is not the sim card. I have since attempted resoring it on multiple computers. If I try to restory from the Itunes logo and USB cable/ emergency call page, itunes give me error 3194 (I know this to be a signing problem but I have no clue why) If and when I put the phone in restore mode the phone will do a full restore, but once completed the phone goes back to the previous state.

I know this is long but any help would be great.
Thanks
Tim

History: First and formost the phone was previously jailbroken with both Blackra1n and Green Poison. In addition to this the host file on his computer did have the extention added to it to allow signing through cydia.

Thanks for the reply, I already removed the IP address from the Host file, this did not fix the problem. As to Tiny Umbrella, I know very little about it, I do have it doen loaded, but the only time I ever used it was to kick my Iphone 4 out of recovery mode, I will read the link, but if it has something to do with signing I dont think it will help.
Thanks
for the help and any additional help you can give.

That worked

I have no clue but unsetting the set hosts box worked. Thank you for the help.