problem with catalyst 8,3 and .4, maybe temp?

[Soujiro]

Hi to everyone, i' have an mobility radeon x600, i've found two days later a problem, when starting 3d applications like glxgears the system crash and shutdow. after some seconds (actually 4-7 seconds). The only way i found to prevent this situations is to set the powerstate on the Low Voltage.
where is the problem?
can it be an high temp?
why only now after 1 month of use of the 8.3 version?

:confused::confused:

sorry for bad english