My 2006 Mac Pro is regularly crashing on startup with a kernel panic. It will chime on startup and usually show me the Apple startup screen with the spinning wheel-- but after that, I get the multi-language "You need to restart your computer. Hold down the Power button until it turns off, then press the Power button again" message. Sometimes it doesn't even get there-- the spinning wheel just freezes, and stays frozen. Every once in a while, the Mac will start up, but the mouse will be so unresponsive that it takes me several minutes to mouse over to Restart so I can try again. (I've checked the mouse on another computer and it works fine.)
• I have one SSD startup disk with Lion, and two HDD startup disks with Snow Leopard. Starting up with any of these three disks results in the problems described above. This suggests to me that it's a hardware problem, rather than a problem with a specific startup disk.
• I tried starting up from my Snow Leopard Install disk. It was able to start up successfully. All the data on my hard drives seemed to be intact, including Lion Install, so I tried re-installing Lion on my SSD. It showed the blue progress bar for a minute. Then it said it would restart my computer in 30 seconds-- at which point, I once again got the multi-language "You need to restart your computer. Hold down the Power button ETC" crash. If even the install disk is crashing, this again suggests a hardware problem.
• I set the Mac Pro to target mode, and used it as a startup disk for my wife's Macbook. It functioned just fine and there were no crashes. Again, confirmation that it is a hardware problem with my Mac Pro.
• I have zapped the PRAM. I have also run Disk Utility, repaired permissions, and verified the disk. This did not fix the issue. (Not surprising if it is a hardware problem.)
• HOWEVER: I put in the install disk that came with the computer originally and was able to complete the Hardware Test. I chose the most thorough option. It did not find any problems.
• This started happening three days ago. I'm not aware of any recent changes to the system that could have caused this. The most recent change I made was installing a Radeon HD 5770 graphics card and an SSD drive, more than a month ago. There was no sign of trouble after I installed either of them (except for some problems putting the Mac Pro to sleep, which is apparently a known issue with the Radeon 5770 in this model Mac Pro).
• Weirdly, after I fiddle with the Mac Pro for an hour or so (run diagnostics, reboot it repeatedly, etc) it seems to start working. If there is indeed a hardware problem, then perhaps something works better when it's warmed up.
Is there anything you'd suggest I try? Or am I stuck lugging it to the Genius Bar? I don't have a car, so this is a bit of a pain…
Thanks in advance for any help you can give!