Hot Keys Not Working Properly

Does anyone know how to correct hot keys not functioning...namely Object/Arrange/Send to Back or Send Backward. The bring forward and bring to front work fine. I tested the keys in other applications to see if it was the keyboard and they work fine. I also went into the hot key preferences and retyped the key combination of command....shift...[ but that didnt work. I am even experiencing problems with shift and the [ key by themselves on one side of the keyboard. However, all keys again work separately. Seems the combinations of multiple keys is messing up somehow. Any help would be appreciated.