PS2 loses time/date info

[lung]

I was wondering if anyone else has experienced this. Whenever I turn off my PS2, it loses the date/time info. The PS2 is brand new, but I did install a Neo4 chip and I am wondering if that may be the cause of this. I guess it is not a huge deal on it's own, as I can just put the PS2 into standby mode instead of turning it off.