Wiardgroup

I'd try some testing to narrow down which module or modules are  
contributing to the problem by disconnecting modules until the problem  
is gone.
  Having another power supply is great for problem solving. If you  
have one module that doesn't get along you can give it it's own supply  
as well as two or more supplies give you the chance to verify or  
eliminate the original power supply as the culprit.

nick