This is getting a little frustrating. I'm having intermittent hardware crashes on my MBP (1st gen) without any consistency. What happens: I turn the machine on and after a few seconds (before the login screen), the machine cuts out with a "plick" as if the power's been cut off. I'll turn it on again, and the crash will happen in the same amount of time (+/- 2-10 seconds). After about five occurrences, the crash will happen immediately after turning the machine on (that will be consistent). You'll hear the startup chime following by a "plick" immediately. Now, this is intermittent, but happens mostly when I get home from work. After walking away from the machine for a half hour or so, the machine seems okay. Weird. The machine is stock (including memory), and I've zapped the PRAM and PMU several times - no such luck. One thing I'm noting is when I finally get the machine working, the "Previous Shutdown Cause" is "-72." Eventually after a number of reboots, it will change to "0." Then the next day (or the day after that), the crashes will happen again, and the "-72" number is there again. Okay, so I called up Apple support yesterday and did some troubleshooting over the phone - no such luck. The support person made an appointment for me to go to the nearest Genius Bar for today. So I went today, and spoke with a Genius. No such luck either - since he couldn't witness the occurrence firsthand, he couldn't do anything for me. Argh. Funny thing is that I received my laptop back from Apple for a previous issue (display issues) in late Jan/early Feb. I never had this issue before then. I've also had the logic board replaced a year and a half ago as well. After each support call, Apple supposedly does a "final test," so my machine was supposedly good in early Feb (by their tests). Any advice on this? I'm thinking this is a hardware issue, since I'm having occurrences of crashing immediately after turning the power on. TechTool Deluxe shows everything as okay. I've already zapped the PRAM and PMU a number of times. Anyone know what a "Previous Shutdown Cause" of "-72" is? Thanks in advance.