I'm in the P.S.T time zone, and I reside in northern CA. Problem: The Navigation System on our 2003 Yukon Denali resets itself to the C.S.T time zone. According to the previous owner, this happened to him roughly 8 times a year. (He was honest enough to share this with me prior to my purchase.) Anyway, I witnessed it for the first time this morning (Jan 2) and I'm 100% certain that the time zone was correctly set to P.S.T as of yesterday afternoon. The previous owner didn't have any luck getting assistance from the dealer, so I was hoping you guys could offer some feedback. Is anyone experiencing this issue? (FYI, I doubt this is relevant, but for the record, my compass variance zone number is set to 4.) Also, the battery is new.