I have a 3GS iphone.It was working alright with iTunes.Recently, it was unlocked. After it was unlocked, the iphone is functioning alright but it is not recognized by iTunes and iTunes stops working, when I connect iphone.Any advice please.

I have a 3GS iphone. It was jailbroken and working alright.But I was not able to upgrade its IOS frrom 4.0.1 to higher versions and many applicatopns were not compatible with this version of the IOS. So I decided to do a factory unlocking. From an website, based in Mumbai, I unlocked it. When I check now in different websites from my IMEI number, my iphone is unlocked. So I became happy that I can now upgrade my iphone. But the events turned to be different.When I connected to iTunes, iTunes stopped working and my iphone did not appear in the iTunes. I uninstalled and reinstalled iTunes after cleaning previous registry of all relatedd components like Quicktime, Bejour,Apple software updates and mobile softwares. I also used msconfig to troubleshoot conflicts in software of Windows 7 ultimate but still my iTunes is not working, when I connect the iphone. If I do not connect the iphone, iTunes is working alright. Can any friend give me some advice how to proceed. I do not like comments like Jailbreaking is illegal and should not have been done. Please advice me what should I do right now. Thanking you all and expecting some valuable suggestions from this expert community.