When crashes occur running hacks or background apps like TealLock, TealScript, TealMaster, the cause is almost always due to running out of stack space.
No matter how much total memory is free, PalmOS limits the processor stack to the amount requested by the current foreground application (an app you launch from an icon). Even though this amount can be very small (as little as 4k) it has to be shared between the current foreground application and ALL currently running hacks, drivers, popup applications and background apps. Thus, if you run too many background apps simultaneously, you may experience intermittent crashes when the stack space is exhausted. Even though the last one you turn on may appear to be at "fault", the real problem is the combination of all apps running together.
Try turning off other background apps, hacks, and drivers to see if one is unusually resource hungry. Background apps include any popup program, driver, font-substitutor, button customizer, text input alternative, or any utility that 'does stuff' when you're not inside the program itself. If this fixes the problem, you may need to choose not to run certain combinations of these apps. Alternatively, if crashes only occur while within a specific "foreground" application, that app may not allocate enough stack space to allow background apps to run. If so, you can use TealMover to boost the amount of stack space requested by that application. Lastly, under PalmOS 4 or earlier, you can also use TealMemBrain to globally boost the amount of stack allocated by all applications.