Recently Blizzard put the real money auction house (RMAH) into effect in Diablo III, meaning you can now buy and sell items for real-world dollars. With the introduction of real money into Diablo's economy comes a greater need for security, both for Blizzard so they don't get sued and for users so they don't lose their money to in-game fraud. So after patch 1.0.3 Blizzard implemented some new security measures for people who digitally buy the game. An unintended bug with the new security was that players can no longer pass level 13 or go past Act I, which obviously has a lot of people in a huff.
As I said, thanks to a bug with the new security, players who digitally bought the game after patch 1.0.3 are unable to pass level 13 or go into Act II. This is a confirmed bug and Blizzard is working on preventing it. The security software not only comes with the bug, but there are some limitations to the accounts of people who buy digitally until payment can be verified (usually within a day, but it can sometimes take as long as 3 days). The following are the restrictions on accounts until payment is verified: