I work with VFP 6.0 spanish version and when I use the CDOW(datetime_exp) function in the design enviroment, it returns "lunes,martes... etc.", but when I install the application in another machine, it returns in english ("monday,thursday... etc.)
>Somebody knows how can I fix it.
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I have the same problem.

It's occurs when you call a .EXE outside of Visual Fox. If you run the program inside the VFP it's works well.

My solution was to create an array

aDia[1] = 'Domingo'
aDia[2] = 'Lunes'
....
aDia[6] = 'Sábado'

and using

? aDia[dow(DATE())]

I hope it solves your problem