Me too. So, this seems to be an issue in the software, either the client or the server. Is there any official position or a fix? (Login out and in again doesn't work, for one).
Same problem here. Tried reinstalling iTunes and now I get an error of -4 instead of the -5002 error I was getting before. I can still access the store itself and preview songs as well as modify my account info. But I cannot access the cart.
I'm getting this same error. I've tried updating enabling My iTunes, adding my credit card security code, and changing my password. Still, I get error 5002. Wwwwwwwwwwwwhhhhhhhhhhyyyyyyyy??
I, too, have been having the same problem. But here is something interesting. On my G5, I have iTunes 7.6 and Leopard and have not been able to get to my shopping cart with the same errors as everyone else. My son has an Intel iMac with Leopard and iTunes 7.5 and he is having the same problems. My husband has a G4 Mini with Tiger and iTunes 7.6, and he can get to his shopping cart and download stuff with no problem. So in our case, the difference is who has Leopard and who doesn't, not which iTunes. Hmmm.
Just changed iTunes preferences to buying without a shopping cart, and actually bought a song. That worked. Then changed iTunes preference back to using a shopping cart, and the error 5002 persists.
Update: I restarted iTunes, tried it again, and got an error telling me my billing address was not a valid US address. I took out the "Apt. #3" and just put "Apt 3" and hit okay; now I am able to purchase.
I'm not sure if this is related but I'm not able to make purchases at all in the iTunes store. I haven't received any specific error number, instead just a message that says the iTunes store is temporarily unavailable. This has been going on for the past 4 days and started with my attempt to purchase a ringtone for my iPhone. Now I've noticed I can't purchase songs at all. I contacted Apple care to no avail, all they've said is that iTunes has heavy traffic and I'll have to be patient. FOR 4 DAYS??
I tried this as well and had the same results. As soon as I switched back to the shopping cart method I received the 5002 error. This is a band aid fix for now, but a fix nonetheless.
I was unable to access my shopping cart for 24 hours since I downloaded the new version of iTunes. I contacted iTunes support, received a reply, I relied to that email and have heard nothing since.
Apple Support emailed me that there may be an item or items in my cart that is causing this problem. They request permission to clear my cart. I just replied with permission, so they haven't cleared the cart yet. They suggest creating a wishlist (http://www.info.apple.com/kbnum/n107961), instead of having a bunch of stuff sitting in the cart for a long time. I will update this post when Apple clears my cart.