From an Apple document to be given to specificed customers who get replacement trackpads: "There is an incompatibility between
OS 7.6 and the new trackpad that was installed in your PowerBook. On a PowerBook Duo 2300c or PowerBook 190 running Mac OS 7.6, the computer may crash after coming out of sleep when the trackpad button is pressed. This problem only
happens with Mac OS 7.6 and non-factory installed trackpad mechanisms. Earlier versions of system software and Mac OS 7.6.1 or later do not have this problem."
The Mac OS 7.6.1 update is expected to be out by next week.