Okay, it sounded like you hit an EA bug with one of your Sims. I researched this issue and found a couple of possible solutions:
1. You could try moving your family (whole family) out of their house and then move them back in. Or you can move both the family and the lot into the bin and then put them back on the lot or another lot.
2. If you tried to reset the Sim to no avail, then you can try downloading Treeaq's Locomotion mod from
MTS. Once installed, try changing the affected Sim's locomotion by choosing Walk and see if that will fix the problem for you and your Sim.
This glitch had been present since the beginning of Sims 3. EA either refused to recognize this issue as an EA glitch or investigated the issue but not come up with an answer to explain why exactly this happened.
Also, if your Sim has the Neat trait and was doing chores, then the Sim will tend to run around cleaning the house.
Let us know if this will help resolve the problem.