ErrorTrap should hard-reset them automatically every night, if you have that mod installed but under some circumstances it does not catch them all. Deleting a jig that is in use will most likely bounce the sims involved. Social Jigs can cause the same type of problem. Often, those markers are generated by the game for spawning stray pets or as mentioned above. They often pile up in the game causing routing issues, resulting in lag. In the case of a SocialJigTwoPerson for instance, they stop sims from walking between two sims having a conversation. Jigs are objects used to temporarily alter the routing system. Here are a few suggestions for finding and flushing Jigs.