ipad 3 model a1430 restore using iTunes fails with unknown error 3

My ipad 3 model A1430 (wifi+cellular) was restarting automatically few days back. Neither i made any changes to its OS nor installed any new applications before this happened. So, i thought to restore it to factory settings. I upgraded itunes to 11.1.4 for windows 7 and started restore. During restore it asked me to upgrade iOS and firmware so i opted for yes. I think iTunes downloaded some latest .ipsw file and used it for updating iOS and firmware on my ipad. It was doing well when all of sudden, during firmware upgrade it gave me unknown error (3) message. I tried various restore options like DFU mode, disabling firewall and antivirus on my machine, validating that gs.apple.com opens up correctly. All was well but my ipad was not fixed.

I also tried to download another .ipsw file 3,3.6.1.4 (something like this) and tried restore with it. This time it gave me 3194 erorr. Tried several times no luck.

Please suggest what can be done to fix it.