You're getting continual kernel panics. Try the usual first (reset PRAM, reset PMU, do a search). You get to safe mode by holding cmd-S, but that won't really help in this situation, even if you get to the desktop. Reboot with your boot DVD in the drive and hold down the C key as you are powering on. Run Disk Utility from the DVD (I forget which menu it is in in the OS install program) and try to repair the drive. You may need to reinstall the OS, worst case.
Steve