Format of `grep-command' with `grep-default-command'

[Christoph Conrad]

[Sorry posting that before without a good subject line]

In GNU Emacs 22.1.50.1 (i386-msvc-nt5.1.2600)
 of 2007-08-15 on CLEOPATRA
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-msvc (13.10)'

* emacs -q --no-site-file
* (setq grep-command '("c:/user/cco/cygwin/bin/grep -nir \'\' *.*" . 35))
* (grep-default-command)
*  Error: wrong-type-argument; Data: (stringp
(c:/user/cco/cygwin/bin/grep -nir '' *.* . 35))

That worked in former times. How to specify default cursor position when
(call-interactively 'grep)?