i have 8.0.1 and 10.4.9 with PT7.1cs10 everything works fine here.. i had a couple of "unexpectedly quit", same as 7.2.3 for me.. very few crashes, expecially compared to 7.1,7.0,or 6 pro. before doing any long osx downgrade or reinstall try disabling all plug-ins in both TDM and AU, in tdm plug-in folder leave only exs24, esb, and the mixer, that is the minimum required to make the dtdm start. remember that only 1 kind of mixer has to be in TDM plug-in folder. as Evan said.. check also for rewire and disable it if it's possible.. i really don't know how to btw, never used rewire more than for test it if you still get immediate crashes it's a combination of sysop/pt/logic, but it sound a bit trange to me.... anyway there is really no reason tu upgrade to 10.4.11, and even to leopard. the minimum system required by logic 8 is 10.4.9 i will not update until programs forces me to do it, as usual ;)