First, try this, if the game glorks when launching, as that symptom may have nothing to do with your content at all.
Go to My Documents--EA Games--The Sims 2 and delete the file there named groups.cache
This is absolutely safe and your game will auto-generate a new one.
That file has a tendency to become bloated/corrupted/glitchy. Periodically removing it and allowing the game to make a fresh one is a Good Thing.
If the game still hangs after doing the above, then follow the tried-and-true (bit a bit time consuming) 50% method for ferreting out troublesome content. See here:
http://www.sims2wiki.info/wiki.php?title=Game_Help:Finding_Problem_Custom_Content#The_50.25_MethodAlso, having Clean Installer installed can be a boon. It will show you duplicate files which can be absolutely safely removed (they are highlighted in pink in CI). (It can also identify all hacks (highlighted in red -- that is not a danger sign, merely a highlight) should you suspect that a hack conflict or an incompatible hack might be causing gaming troubles.)
Clean Installer can be obtained here:
http://sims2pack.modthesims2.com/Handy hints regarding CI:
1) After it has generated a list of your Downloads (which can take a while to complete), click the MD5 tab in CI. This will reorganize the list and group duplicates together. Remove all but one of the duplicates.
2) After that, click the Type tab in CI. Look for any typed in the reorganized listing called 'Collection' in the Type column, and move those to your My Documents--EA Games--The Sims 2--Collections folder.
3) Also look for any labeled Empty Folder in the Type column, and remove those.
Be aware that if you use the Remove File option in CI, that file is totally gone and there is no way to undo or retrieve it.
Generally speaking, the only kind of files that belong in your Downloads folder are .package files. If you have .zip, .rar, .jpg, .png, .bmp or any other types of files in the Downloads folder, either move them someplace outside of your game (should you want to keep or store them) or delete them.
In the Collection folder, there should be only .package files (those which are labeled as Collection in CI) PLUS any image files (usually .jpg) which accompany them.