Your kernel version is what you usually see on the boot menu, or can be found by doing uname -r at the terminal prompt.
You might want to consider upgrading your BIOS, as that might provide fixes for the issue.
Also in the BIOS setup screen, you may also want to disable boot from network, as perhaps it's kicking into that mode for some unknown reason, although I can't imagine why.
Does the machine run fine for extended periods of time? If not, you should make sure that all your cooling systems are working effectively.
So to sum up:
1) Install all latest ubuntu updates with the update manager
2) Disable network booting in the BIOS
3) Upgrade your BIOS version with the flash utility from the manufacturer's website if necessary.
4) You could try changing ACPI to s1 state instead of s3... usually there's an ACPI 2.0 option.