What I can't understand is if I go over to a Mac and save the same one color document as both PSD and JPG and re-open them and sample, it shows the same color value. If I do the same procedure on PC the values are slightly off between the two files.
Adobe wants me to delete ALL my Adobe programs and install everything again. I did that with my Photoshops and it made no difference.
Then you have different compression settings. This works the same way regardless of operating system. It's only a matter of degree with the compression setting, but even maximum quality will degrade the file some. Do not use jpeg if you need to preserve full data integrity.
There is no point in reinstalling. That won't change anything.