You're having a kernel panic. Kernel panics are usually caused by a hardware problem – frequently RAM, a USB device or a Firewire device. What external devices do you have connected? When trying to troubleshoot problems, disconnect all external devices except keyboard and mouse. Do you experience the same problems?
Will it boot OK using your system install disc?
Do you have an Apple Hardware Test disc? Running the Apple Hardware Test in Loop Mode is an excellent troubleshooting step for finding intermittent hardware problems. It is especially useful when troubleshooting intermittent kernel panics. If Loop Mode is supported by the version of the Apple Hardware Test you are using, you run the Extended Test in Loop Mode by pressing Control-L before starting the test. Looping On should appear in the right window. Then click the Extended Test button.The test will run continuously until a problem is found. If a problem is found, the test will cease to loop, indicating the problem it found. If the test fails, be sure to write down the exact message associated with the failure.In some cases, RAM problems did not show up until nearly 40 loops, so give it a good run.
May be a solution on one of these links.
Mac OS X Kernel Panic FAQ
Mac OS X Kernel Panic FAQ
Resolving Kernel Panics
Avoiding and eliminating Kernel panics
12-Step Program to Isolate Freezes and/or Kernel Panics
Cheers, Tom 😉