Usually that's an indicator of a dead motherboard battery. (The one that keeps your clock working)
thanks, this macbook pro is the latets unibody so I guess you could be right, but then again, its only a couple of months old.
any way of checking this?
"any way of checking this?"
Not without taking the bezel off the back of it and pulling the battery.
If it's new, Or even less than a year old, take it to your Apple Store and have a Genius take a look at it. Odds are if the battery is dead (it happens occasionally on new Macs) they can usually replace it while you wait. At worst they'll have it overnight.