After a survey of members at N99, it was found that it is best to keep your Sims 1 Downloads folder below about 2.5 to 3 Gigs - that may sound like a lot but it can be achieved very quickly by a dedicated downloader! (This doesn't include walls, floors, or skins.) If you go over this (for some it is as high as 4 Gigs) - you MAY avoid random unexplained crashing of your game. Of course, more common causes of such problems are insufficient space on your hard drive, not enough RAM (memory), or failure to defrag the drive regularly, or use the checking programs regularly, for both skins and objects.
If you find you have masses of downloads, one idea may be to make a dedicated folder of Themed downloads - say Christmas - with its own Hood of course - and write the whole thing to a CD or DVD; pulling it in as required. This avoids those nasty culling sessions when you have to choose what to delete and just KNOW you will use it one day... This process is MUCH easier to do with SimEnhancer Object Manager. Simply move the item to a folder elsewhere on your drive for temporary storage while sorting. You can even name the folder something innocuous but meaningful to you, such as "Christmas Things" and leave it inside your The Sims folder. The game only sees the folders it KNOWS to look for, so should ignore this folder.