In win XP, you can't use Ndivia Video Card, because it don't have a proper driver for win XP.
You you should disable this video card in Device manager.
- Try to install latest driver for your Intel onboard card.
- Try to change screen resolution to a smaller resolution.
If above steps still don't help
Finally,
SYMPOM:
The system shuts down unexpectedly during normal usage.
This tip is for the following regions: North America, South America, Central America, Western Europe, ASEAN adn RUCIS
AFFECTED CONFIGURATIONS:
All U460 models configured with discrete graphics that were manufactured between 1st June 2010 and 15th August 2010.
(U460S is not affected)
SOLUTION:
Root cause:
There is a defect that affects a small percentage of the heat-sinks used on the U460 that causes the graphics processor to overheat, causing the system to shutdown.
Solution:
Any customer who experiences repeated unexpected shut downs should call the support number listed in their user guide. This can also be found at:
http://support.lenovo.com/en_US/detail.page?LegacyDocID=MIGR-76613
Lenovo will arrange for the system to be sent to the depot to have it reworked.