On some systems, you may encounter an error during setup because the version of MFC42.DLL on your system is outdated. Since this system file is probably in use, it may be difficult to replace it with the newer version. If you are installing a recent version of Res-Q (built on or after July 5, 2001), the setup program will include a newer version of this file. To manually replace the file, use Microsoft's INUSE.EXE program. To view instructions and download this program, click here.