Error 42003 when synching apps to iphone

Question

Aargh!
I am trying to sync my songs on my iPhone 4, but I can't get past the apps sync. iTunes complains that "This computer is no longer authorized for apps that are installed on the iPhone 'My iPhone'. Would you like to authorize this computer for items purchased from the iTunes store?"
When I attempt to authorize my computer (which was authorized the last time I sync'ed my phone a week or two ago), I get the message: "We could not complete your iTunes Store request. An unknown error occurred (-42003). There was an error in the iTunes Store. Please try again later."
I also get this error when I try to listen to a song in iTunes that I had purchased from the Apple store.
I have no trouble accessing the Apple store through iTunes. My account shows that I have 4 computers authorized for my account (5 is the max, right?).
I have double-checked the user id - it is the same one that shows in the app's "Get Info" (it's the same one I have always used). If I enter the wrong password, I get a password error, not the 42003 error.
I did everything in http://support.apple.com/kb/TS1389 and still have the problem.
I have tried to de-authorize/authorize my computer from the iTunes/Store menu, but that also gives the -42003 error.
I have uninstalled iTunes, restarted my computer, and reinstalled iTunes -- still have the problem.
I have run iTunes/Help/Run Diagnostics and all the tests passed.
Naturally, this all happened 4 days after my 3 month iPhone warranty expired, so I can't talk to a real support person unless I want to pay them $29 for their unknown error. And one of the times I was trying to solve the problem, I accidentally clicked the "Don't authorize" button and iTunes DELETED MY ANGRY BIRDS APP!! Of all my apps, the only one that had any data I cared about is the only one that got deleted! My apologies for shouting, but I am so frustrated I could cry!!

Answer 1

I just updated to iTunes 10.2, and the authorization issue has magically gone away (note that Apple released iTunes 10.2 on 2011/03/02, but iTunes did not notify me of the update; I just happened to check for myself in a last ditch effort to resolve this problem). Not a very comforting solution, but at least Apple is now letting me have my duly purchased songs and apps back.
For future reference, this was actually a problem that I could have reported via email -- I apparently chose poorly when going down the online help path. Instead of considering this an iPhone issue, I should have gone to Support -> iPod+iTunes -> iTunes. Then, under "Get Customer Service," select "Authorization" -> "Troubleshoot authorization problems" -> "Tunes repeatedly prompts to authorize computer to play iTunes Store purchases". From there, you can send an email for support.