Does this also hapen after you restart the PC. Make sure the file property
isn't set to "read only" in Explorer. If this is not the case try running
scanpst.exe against it and see if it comes up with anything.
I am having the same problem. PST files are stored in the
home drives (network share) of my users. I have had to
copy the pst file in question, rename the old pst file and
then rename the copied pst file to the original name.
Then the error message does not return. However, within a
week or so the error message returns.