Illustrator Colors

[macdadad]

I've encountered this "situation" several times in different versions of Illustrator. When I'm working on a vector artwork, I assign CMYK colors b/c I would eventually be outputting it in CMYK often. So I work on the artwork, save then close the file. HOWEVER when I open it again, the color values change!. For example (for discussion purposes) I assign 100% Black, 0% Cyan, 0% Magenta and 0% yellow to a design element before I close it, when I re-open it at a later date, the values become, for example: 84.95% Black, 62.58% Cyan etc...etc...
Is this an Illustrator thing or a Mac thing? How can it be fixed? I've seen it happen on different Macs and different Illustrator versions since I'm on-call for different clients most of the time. They call me and I do the work in their offices. The color shifts are very annoying to say the least.
Many Thanks in advance!

[Chris....]

When you create the document are you selecting CMYK? I opened a new document and when I used RGB and filled a box with a cmyk build it converted to rgb when I reopened it. When I started with a CMYK document it was fine.

[macdadad]

DUH!!!!!! where did my brain go???? hahahaha of course! Thanks Cris!!! for the longest time it never occurred to me!

Thanks again and more power to you!