Just noting that I also have this error in QC 11.0. I was copying some tests from different projects into a new one. I had no problem with the first couple of projects, but then got to a project that just won't let me copy anything. Always produces the 'Failed to paste data' error.
Obviously a problem as instead of getting all that you need in a few minutes, you must manually re-enter all of the data. It wouldn't be quite as bad if the export/import functions didn't strip out all of the formatting and CR/LFs forcing you to re-edit it all to put it back. Anyway, easily a few days of work instead of a few minutes. Thankfully, I am not moving many tests.
