We have a situation that the Magento cache is refreshed every night automatically. Afther this a script runs which visits every page to build the cache and every page will be fast. This works, however when someone is working in the admin (changing products, changing textpages etc.) the cache becomes invalid and I have to visit the product page again to build the cache.
My question is, when does the cache become invalid and how can we prevent this. Thanks in advance.