Exception: The file or directory is corrupted and unreadable

[MikeWilliams-UK]

Exception: The file or directory is corrupted and unreadable.

This seems to be happening if the user's profile folder is read only.
It has also been seen sometimes when the profile is mapped to a network drive.

The file or directory is corrupted and unreadable
  at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
  at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
  at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
  at System.IO.StreamWriter.CreateFile(String path, Boolean append, Boolean checkHost)
  at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize, Boolean checkHost)
  at System.IO.File.InternalWriteAllText(String path, String contents, Encoding encoding, Boolean checkHost)
  at System.IO.File.WriteAllText(String path, String contents)
  at Chem4Word.Chem4WordV3.LoadOptions() in C:\Dev\vsts\chem4word\Version3\src\Chem4Word.V3\Chem4WordV3.cs:line 345