First of all, my thanks to Lord Blackadder for assisting me with another facet of the problem yesturday - 'preciate it! Before I go and throw good money after bad, I would like a layman's definition of the following error message when booting with the Apple Hardware Test CD: INVALID MEMORY ADDRESS AT: %SRR0: 00034870 %SSR1: 00003030 The computer (Dual 1.25 MDD) boots up fine, and performs most of the time well. I first noticed the problem when: 1) Performing memory-intensive tasks, such as rendering with Final Cut Express 2) Attempting to "zero" an HDD Swapping, removing, replacing RAM sticks did not change the error message; the microprocessors themselves have already been replaced most recently (I found that when these fail, the machine will not boot at all - is totally dead). Before investing in a new main logic board, any and all input with regard to this anomally would be appreciated. Thanks!