Latitude D620 Flashing battery indicator

Hello all...

We have multiple Latitude D620's here in the office that have flashing battery indicator lights (the light is on the laptop, not the battery) - the light flashes amber 4 times, then goes back to green and repeats.  Normally we'd think that there's some kind of problem w/the charge but when we undock the laptop (from the Dell docking station that came with the computer) we can still work on the computer for hours w/o a problem.  The systems that this happens with including my own are most typically in the 6-12 month range when the symptom first appears.

Is there a known issue with the D620's and the battery charge indicator?  Is there some other problem we should be aware of?

Thanks much in advance...

PhoenixUser