That is one heckuvan accusation to make and a disgraceful comment particularly if you have no proof that the software is not genuine. Problems have even been known to occur on trial versions to you know.
I have a legitimate copy of Corel Painter X and even with it this problem too exists - ever occur to you there might be a bug in the software? I have the Mac Version and I asked a colleague of mine to check this out on her (legitimate) IX.V for Windows....
The problem does exist and it is a bug (shame corel have not got round to fixing it yet!). What if boild down to is that even though not visibly ticked at times the palette transparency option is activated. Just tick it, tick it off again and it should work fine, Worked okay for both of us on different versions and on different OS.