Memory: 6GB DDR2 SDRAM (2gb in slot 1, 4gb in slot 0)
Problem: On startup, computer would beep three times, pause, then repeat the three beep pattern. The one time that it did restart, I ran verify disc and it found errors.
Boot from a CD -> Beeps
Re-seat the RAM. -> no change
Take out one RAM stick -> was able to boot and run disc utility repair
Blew out the RAM socket with compressed air.
Re-seat both RAM sticks in reverse order (2gb in slot 0, 4gb in slot 1). -> Boot went fine.
So, now I don’t know if it is a memory problem or a directory error. I skipped too many steps while troubleshooting. After several reboots, the problem hasn’t come back. We’ll have to wait and see.