iPhone mail stuck at "checking for mail"

I've seen this question asked severl times and I've tried all of the troubleshooting suggestions that I've seen on these forums - none have worked, so I'll ask the question again for my circumstance.

I have...

confirmed internet connection

confirmed password

quit the mail app (multitasking)

turned on and off airplane mode

restarted the iPhone

deleted one account

reinstalled the one account

deleted both accounts

reinstalled one account at a time

I have an iPhone 4 with OS5 installed. I installed OS5 about a week ago, and all had been working fine. Most recent mail update was yesterday just after 1:00pm. Since then my two accounts have received between them 12 emails but I haven't been able to sync them to my phone. This isn't a push problem - even in the mail app I'm unable to get the mail. I don't get any error about unable to connect to server, it's simply stuch at "Checking for mail..." indefinitely. The longest I've let it sit at checking for mail before just putting it away was 10 minutes. I have one gmail account and one Exchange account. Neither work, and as I said before, I've tried having only one loaded at a time, and neither have worked. I honestly don't know what happened between yesterday at 1pm and last night, when I first noticed the problem. I noticed the problem before having synched my phone to the comp, and since I've synched it and still see a proble. The only change that I've done in terms of software was to download AppShopper. Aside from that, nothing has changed.

I've tried everything that I've read about and can think of and I'm still stuck, sooo I come to you guys.

Thanks for your help.