I have solved a similar problem by placing an empty picture frame of the same size under my 600x while on my lap, thereby allowing it to cool. No problems since.

THINKPAD 600X

Every time I turn it off, the color quality setting changes from 24 bits to 8 bits. When it's back on, I have to reset it manually. I am running Windows XP Professional o.s.

What could be the problem? Please advise.