Push Notifications Not Working After Jailbreak

Hi all, I jailbroke my IPhone 4 on thursday with the redsn0watt jailbreak for IOS4.3.1 (the first jailbreak for 4.3.1, not the updated RC11). I then spent an hour or so downloading various apps from Cydia; it's great! However, there is one rather big issue. I realised on Friday that I hadn't received any push notifications recently from Boxcar, yet mentions and direct messages were coming through on Qwitter. When I opened Boxcar, I got a pop-up message stating: "Connect to ITunes to use push notifications." I opened Foursquare, Facebook and the official Twitter app and was greeted with the same message. I went in to settings and disabled and re-enabled push notifiations with no affect. I then did what it told me to do and connected the phone to ITunes and synced it; still no luck. I am still able to get alerts of SMS messages and incoming calls, but nothing else. While everything else is working fine, I would really appreciate having my push notifications back. I am assuming that one of the packages/apps I installed caused the problem, but i've installed a lot so it would be hard to go through them all and find out which exact one had caused the problem. I know that a restore in ITunes and a re-jailbreak would probably fix the issue, but I was wondering if anyone had any other ideas before I did that? FYI, i'm using an IPhone 4 32GB running IOS4.3.1 jailbroken (not unlocked) on Vodafone UK. Thanks in advance, Robert