grep command adds "NUL"

[Leo]

hello

i try using the grep-comand.

so i type:

        M-x grep RET 'spider' *.pas

but emacs creates buffer *grep* with the following lines:

        cd C:/mydir/
        grep -n 'spider' *.pas NUL
        spidermain.pas:368:     115  spider:= TSpider.Create;
        grep: NUL: Permission denied

        grep exited abnormally with code 2 at Tue Dec 03 15:59:34

looking in the elisp source tells me, that emacs wants to add a null-device.
why that?

ta for help.

cheers, leooo