Visual Basic for Applications Reference
User interrupt occurred (Error 18)
Specifics
The process of breaking execution is useful, but if left unhandled, it results in termination of the application. This error has the following cause and solution:
A user pressed CTRL+BREAK or another interrupt key.
In the development environment, continue execution. To provide for the occurrence of this condition at run time, handle the error in an appropriate way.
For additional information, select the item in question and press F1.