Just to echo a couple thoughts expressed and give my opinion:
Leave your studio alone. Do not access the Exchange right now, either uploading or downloading. No reason to panic at this point. Just take a break.
As for the viability of Custard:
It works beautifully with every expansion and stuff pack installed.
It has one limitation I know of: it does not seem to catch custom skin color.
Also, you cannot Custard worlds, as they are not actually Sim3Packs, but links.
As many of you are, I am very happy with Custard, as it it amazing what files can include without the knowledge of the creator. Stuff hides, it is malicious. If those who use Custard don't already, also use Dashboard; it cleans the caches of your game which can literally suck the CC you cleaned out back in, like it is in storage.
Dashboard was also created by Delphy who created Custard.
If I am in anyway in error, do inform. I hope only to help.
Sharon
