Color Settings Problem

I've got a problem with my color settings. My midtones are a sort of magenta instead of grey, but only in photoshop. If i open an image outside of photoshop, the midtones are gray again. This is a problem. My color palette shows magenta where gray once was. Just asking for a little help here, i'm not too experienced with the settings, and I was wondering how to fix/reset them. I've tried reinstalling, and that doesn't work.

Thanks

Che Ng

Run Adobe Gamma, as explained in the forum FAQ.