Could definetly be the battery especially if you still have the original battery. I was getting alot of those errors before I replaced mine.
2006 BMW 325i Titanium Silver
Mods- 19" AG M310's hypersilver, drilled and slotted rotors, OEM rear spoiler, OEM exhaust tips, corner delete mod, carbon fiber wrapped trim, Viper 5904 Alarm + remote start
Audio upgrades- Alpine S920HD, JL XD600/6, Jehnert XE200, Morel Hybrid Ovation II, Audioque 2200D, 2 Alpine SWR 12d4's (forward facing sealed from trunk)