The last few days I’ve been running into an error in SolidWorks Simulation.  Sometimes I can get a run off without it, but it seems to be more and more frequent.  The error says:

The Iterative Solver stopped.\File error. Hard disk may be full.

File access rights may be inadequate.

No results saved.

Of course, the error only shows up after about an hour of processing.  All files are local, and there is plenty of disk space (>250 GB).  I haven't changed anything with antivirus programs or any other setup recently; I have been performing many simulation runs with no issues, and then this seems to have cropped up out of the blue.  Any ideas?