It seems that your controller is sending out some MIDI signals to Giga (Have you tried sequencing something and then looking in the sequencer track to see if you can figure it out?)
If the problems have started recently, I suggest resetting your controller to factory settings and reinstalling your MIDI interface if you have the patience.
Other than that, I\'ve heard before (I think from King) that bad physical connections (cables) can cause that, so you might try getting a new MIDI cable or swapping cables to see if that helps.
You should be able to analyze the problem with MidiOx... available for download free. With it, you should be able to see the incoming midi stream, which should pinpoint the problem. I\'ve found it to be an invaluable tool, for routing as well as for troubleshooting.