[TYPO3] cache settings

[Andy Pailthorpe]

I am havign problems wiht the page cache randomly being emptied.  At the
moment the cache is set to expire after a week, it normally lasts nearly a
week and will then clear itself in the middle of the day, when I have set it
to clear at midnight, and will randomly clear itself every so often for the
rest of the day.  Has anybody else had this problem?  could it be one
particular page or compenent clearing the cache?

Cheers