Sims2 it keeps blocking n i donno why ..any help plz?

My PCs memory is mostly free n same with the space on my drivers.. the settings on the game are low n i downloaded objects from the net..could it be cuz of them? (n how can i delete some of the objects -cuz some dont work- ? does it exist any program so i can see a preview of the object?) i need help T_T ( i got sims2 open 4 business, pets, season, Glamour Life Stuff n night life )