what exactly is groups.cache?

[coolreko]

I hate to be a nuisance, but what exactly is group.catche?
Some of my sims are bugged, and I was wondering if that was causing the problem. The Swain guy in the University expansion won't even do anything on his own, along with the other male roommates, without some queue coming up that say "delete, reset, or cancel." I have tons of hacks/mods but they are updated with freetime, so I'm not really sure whats causing it.

[BeosBoxBoy]

groups.cache is a part of the game's content catalogue. It severs as the master index of the catalogue.  The content catalogue is comprised of several files that include the thumbnail packages ( and in Pets EP and later EPs accessories.package )

There is a similar file used for the catalogue in BodyShop: cigen.package - this file differs from the in-game catalogue in that all the various parts are all contained in this single file.