Many comments on various issues in 2.0 or 2.0.1 upgrades. Many questions have been answered numerous times. I am adding a summary of a lot of the problems and solutions in this post for reference. I can also update it over time if we need it.

Problem: Mail App crashes after my update.
Solution: This is caused by the sync of the backup from iTunes. The permissions on the mail folder are incorrect (it’s owned by root). The easiest fix is to run bossprefs, click more, and click “fix user dir permissions”. You may need to reboot.

Problem: I have AT&T or a contract carrier. I jailbroke with your guide and now I have no service.
Solution: You activated and you shouldn’t have. iTunes will activate for you but because you clicked the activate button, iTunes did not get to activate. Now your account is not validated. You need to redo the steps and not check activation on your image.

Problem: I have an unlocked 2g phone. I updated to 2.0. Now I get incorrect SIM.
Solution: You did not activate and unlock. Redo the steps and make sure you activate and unlock. In winpwn, this is “activate” and configure boot neuter on the last tab. (See my guide). On osx, this is saying “I am not legit” when asked in pwnage.

Problem: Winpwn IPSW will not complete. It just errors out.
Solution: This one is caused because the size of the image is larger than the partition space. Generally resizing the partition to 550mb solves it.

Check out the rest of the article HERE.