Advent 7110 shuts down.

Question

Advent 7110 shuts down. P.C. World have had it back several times. No improvement. Seems that fan is not in right place i.e. under lap top. Could it be an overheating problem in which case there should be many complaints with this model. The turn off is like this: mouse freezes, all goes off instantly. Turn it back on and all is normal. Nothing in event log.