CUSTOM.pll modification

 Hi, I have modified the CUSTOM.pll file and added an event trigger that will fire in the OM (sales order) form.  CUSTOM.pll was compiled and a new plx generated ok.  When the Sales Order form is run and error pops up, ORA-01403, and the details indicate a 'WHEN-NEW-ITEM-INSTANCE' trigger raised an unhandled exception.  After selecting OK on the error box a couple times the form proceeds and the customization then works ok.  The mod I made does not have that trigger and this error also pops up in other modules using other responsibilities.  When I shut off the custom code...the app