Thanks again,I did manage to delete the preferences using your method above. but again, copy and paste using PSD files still not resolved.
Copy and paste works for PNG GIFF JPEG files but not for PSD
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OK thanks to Curt Y, I suggest the solution is to do the preferences first, then the purging.
I went back and purged the clipboard again after resetting the preferences and now it appears to be fixed.
thank you 