Too many open files.
a) CONFIG.SYS – Files=### Increase ### Reboot.
Reported by Reset, Rewrite, or Append if the program ha stoo many
open files. DOS never allows more than 15 open files per process.
If you get this error with less than 15 open files, it may
indicate that the CONFIG.SYS files does not include a FILES=xx
entry or that the entry specifies too few files. Increase the
number to some suitable value, for instace, 50.