IPhone 4 jailbroken. Won't connect to iTunes?

I have an iPhone 4 that is jailbroken currently running on ios 5.1.1 I recently tried to update my phone to the current software and it won't let me connect to iTunes on my laptop. I tried to update from my phone but it wouldn't load. I also installed Siri using cydia and was wondering if this could be a factor. I tried to delete it but had no luck.

OK, here's the thing… When you jailbreak an iPhone you DO NOT connect it to iTunes. You DO NOT download the latest iOS when it comes out. Because your phone is no longer running iOS, and it won't talk to iTunes.
If you want to update your phone, you need to get a more up to date version of your jailbreak software.
Alternatively, do a hard reset and restore it to be an Apple iPhone again. Then it will connect to iTunes but you'll have lost the jailbreak features.