How do I convert an EFI System Partition into a normal GPT partition?
Solution 1:
Thanks to a friend, I discovered you can use gdisk from the GPT fdisk suite.
For the benefit of others, use gdisk 0: (substitute the number of the affected drive). Type p to print the list of partitions. The EFI System Partition will have a type of EF00. Enter t to change the type, select the number of the partition, and then type the code for the standard Windows partition, which is 0700. w will then write the changes, and after a reboot you should be back to normal.