the flashing light is telling you that the machine is in standby ......
there .... I've said it .....
the light flashes for two reasons
1 When it's CHARGING
2 When Its in STANDBY, Hibernation .... or if Vista .... when it's SLEEPing.
3 When the battery needs charging
to stop it
mod the power save settings ...so that the machine switches off
btw neil is right ... batteries should always be charged for 24 hours before switching on