T-Mobile in the U.S. has halted sales of its Sidekick mobile phones after a series of gaffes left users unable to access their data, and in some cases led to the data being deleted permanently. According to Microsoft/Danger—Microsoft purchased Danger, the company behind the Sidekick, in February 2008—the service interruption began on October 2, and continued for the next few days for most users. Some users never had their data restored,…