CPU Temperature

I'm certain that my CPU (P4 3.06gHz) is running far too hot and is the cause
of my unstable PC. The manufacturer claims the temp is normal for this type
of system - which is more like a laptop than a desktop, as the motherboard
and cards are built in behind the TFT screen and the hardrive is built into
it's base.

According to Sisoft Sandra, the CPU runs at 108-113'C during normal
conditions an the top of the unit is hot to the touch. Can I rely on this
software's reading?

I've also heard that a P4 powers down when it reaches are certain temp to
prevent burn out - is there any software that can prove that this is
happening?

All help will be appreciated as this system has been in for repair 3 times
in 6 months and I'm thoroughly sick of it, and I want to look into the
possibility of getting a refund if they cannot supply me with a stable
system.

Thanks in advance