Users on Linux have reported they get the following error while running DbVisualizer:

java.lang.NullPointerException: Failed to retrieve atom name.
   at sun.awt.X11.XlibWrapper.XGetAtomName(Native Method)
   at sun.awt.X11.XAtom.getName(
   at sun.awt.X11.XDataTransferer.getTargetNameForAtom(

This problem is related to the X server on Linux. Some have reported that re-starting the X server fixes it while others confirms that restarting the X clipboard helped (