PlayStation 3
Sony confirmed that there was an error and stated that they were narrowing down the issue and were continuing to work to restore service. By March 2 (UTC), 2010, owners of original PS3 models could connect to PSN successfully and the clock no longer showed December 31, 1999. Sony stated that the affected models incorrectly identified 2010 as a leap year, because of a bug in the BCD method of storing the date. However, for some users, the hardware's operating system clock (mainly updated from the internet and not associated with the internal clock) needed to be updated manually or by re-syncing it via the internet.

Q: What clock unrelated to the error in the PS3 had to be updated in some cases in order to fix the bug?
operating system clock