I have a clean installation of 12.04 32bit on Dell Gx620 USFF.
When I switch on computer after few hours (when the computer is shut off), then computer reboots during startup. Ubuntu logo appears then restart, this is repeated few times and then system starts normally.
Strange this is that this happens only when computer is shut off for long time, when I shut off computer and then switch on, Ubuntu starts normally.
memtest, changed BIOS battery, tried clean installation and nothing helps.
Please see the log file here.