Alert returns .bin attachment


We have created a windows event log check that uses the check_nrpe plugin to run a remote vbs script on the client machine to poll the Windows Event Log. On occasion, and not on every machine, nagios will return the check data for the alert as an attachment in a .bin format.

Is this a configuration issue? A problem with return value from my script (Perhaps too long?) or what might cause Nagios to return the alert message as an attachment?