Error DBFNTX/1001 Open error: filename.ext (DOS Error 4)

DOS error 4 means the operating system will not allow more open files, while SRM wants to open another file.
-> Open the file C:\CONFIG.SYS with a text editor and look for a line with:
FILES=..
Change the line this:
FILES=50
If you cannot find this line, add it.
After this, you must restart your computer to let the change have effect.