once you have determined that it is not a voltage problem then try what i suggested earlier
do a switch test and when you press the start button see what switches are activated when you press the button. also press on the switch in the ball shooter lane and see what comes up.
Try taking the game out of free play and get rid of all the credits and then press the start button and see if it resets with out any credits, also try pressing on the shooter lane switch and see what happens.
if for some reason the slam tilt is being tripped and resetting your machine it will not reset the machine while in test mode but it will when not in test mode.
it really sounds like a switch matrix problem (incorectly wired diodes or problem on the cpu) to me.
If someone with a can verify what a data East Star Trek 25th does when the slam tilt is triggered ( does it just reset or does it say "SLAM TILT" )
Strangeways is on the right track
I still think it is within the switch matrix, and it will be a miswired switch or diode. Can you double check the orientation of the diodes you replaced, as I think you replaced some diodes in the trough switches and the launch switch ?
I would be checking the wiring / diode on the trough switch 1 (left)
