I reinstalled the first time, and the game still didn't load, so I did it a second time, and got rid of all the custom content, and now it works just fine - that is all the peggy hairs, and clothing from all-about-style, save for 3 of the patterns that DID work and didn't cause problems.
I've just installed the hair (not the clothes) and it's working fine, so it must be the clothing files that cause problems.
thanks for your help everybody!
Ps. I followed the Installer Helper Monkey instructions. They work!