Thanks up front for assisting me with this one.
The changes made per FxCop would be lengthy to list as I am using it as a best practice guide. I did make changes regarding security and CLSCompliance, but both changes have been commented out and the situation persists. It is almost like the designer portion of the code is not being read.
Security changes to main form (commented out):
//[assembly: IsolatedStorageFilePermission(SecurityAction.RequestMinimum, UserQuota = 1048576)]
//[assembly: SecurityPermission(SecurityAction.RequestRefuse, UnmanagedCode = true)]
//[assembly: FileIOPermission(SecurityAction.RequestOptional, Unrestricted = true)]
CLSCompliant changes to CtrlPlayer UserControl (commented out):
A simple call to change the text of a groupbox on the control yields the exception. If I comment that line then the next line (and the next...) it will generate the famous "Object reference not set to an instance of an object" error on each subsequent line.
This one is not going to be easy to find (although the resolution probably will be).