Gateway Notebook Model 400 Series

I teach at a library. We use 5 Gateway Model 400 series notebooks for
students. We run off the transformer brick, not battery. All
notebooks have Sanyo 8 cell Li batteries installed. One notebook
starts slowly. Requires me to depress power button for 10 - 30 sec.
before the LEDs light up. I have switched batteries and power
transformers with good machine with no improvement. All batteries
indicate full charge. I have reset CMOS to default, no improvement.
All running XP with SP2. No new hardware since purchase.

I have scanned many of the posts in this group and do not see any that
talk about this problem. I would appreciate any help I can get.
Thanks
Steve