Are you on the computer now? In other words, was this a temporary problem?
If you are continuing to get that error on another system, you may need to both repartition the drive and reinstall the operating system.
However if the error is ONLY being caused by a missing himem.sys file, you can replace it by booting with a startup floppy for the operating system. At the a:> prompt enter:
copy himem.sys c:\windows
Then remove the floppy and ctrl-alt-del to reboot.
^ indicates where the spaces go: copy^himem.sys^c:\windows
Unfortunately the "command interpreter" message often indicates a corrupt ms-dos partition. You can check this from the a:> prompt by entering:
fdisk /status
(there is a space before the /)
You should see the correct partition information for your drive displayed. If not, the drive has to be repartitioned and the operating system reinstalled.