Originally Posted by alb_mic

why runtime error is occured?

In most cases, runtime errors are actually problems in your Windows system rather then the program trying to operate and is subsequently causing the error message.

A common source of runtime errors is a corrupt registry which causes programs to malfunction. For example, the runtime error #7 which means a memory problem may not really have anything to do at all with a shortage of memory on your computer - rather is could be a problem resting in the file structure of your computer which causes your program to malfunction.