What is .sl1 file? I have a part on which I am attempting to run a Simulation for movement/translation of a latch and when I click on run I get a ".sl1" file error. This is the second latch on the part. The first simulation ran fine. I saved a copy of the part and results file then modified the part (assembly cuts) to get just the second latch, re-meshed and then clicked on run and now get the error message. Why? I have to closed the file, reopened it and tried to re-run the simulation and then Solidworks crashed..