If you copy coloured text and paste it, the inserted text appears black. If you copy a text with a dropshadow and paste it, the dropshadow changes to a embedded picture. If I turn off QuicKeys, it works everything fine (?). In CS5 we don't have this problems.
Answer from startly.com (developer QuicKeys):
Like you said it looks like a bug in Illustrator CS6. If QuicKeys worked with CS5 and all you changed was CS6 then it was something that Illustrator changed. I'll put it into our database to see if there is anything that we can do on our end to fix their problem for a future release of QuicKeys. No estimate of when that would be.