The following message appears when my laptop crashes.

Windows has encountered a problem and has shut down.
stop: 0x0000008E(0x0000005,0xF7A79AAE,0XA831D30C,0X00000 000)
mbxstby.sys-Address F7A79AAE base at F7A79000, Date stamp436off3C
Beginning dump of physical memory
Physical memory dump complete'

I then have to turn off then turn on, to start the laptop. This normally happens when it has been sitting idle for about 30 - 45 min. Does not happen all the time, but is pretty often.
Please help

Welcome to D-A-L.

Start here;
"STOP 0x0000008e" error message during Windows XP setup

It's also possible you have a RootKit "invasion", but eliminating RAM faults should come first.

I do not have a Windows XP Set Up disk, is there another alternative.