This is an issue that I have seen bandied around on the Lenovo site, but with no clear resolution. When the T61p is removed from the docking station (correctly), it is used as normal.
When the T61p is returned to the docking station, as soon as it is clicked in, the machine switches off. (dirty shutdown). Even at times, pressing the power button on the docker or the laptop will not bring it back on, you have to remove and reinstall the battery for the power to come back on.
Has anyone else heard of this??