One of the advantages of an operating system such as Windows is its ability to run more than one application at a time. However, this advantage can also create hazards when you are testing and debugging an application.
Windows is a robust operating system. When Windows is running in protected (standard or 386 enhanced) mode, it can usually terminate an application that encounters a fatal error (such as an invalid handle) without affecting other applications. A fatal error or even a GP fault in an application very rarely causes the entire system to crash. However, it is possible to cause system failure in other ways when you are testing and debugging an application.
Because of the risk of system failure, you should always save all file buffers to disk before testing and debugging your application. You should also avoid running other applications while testing and debugging your application if a general system failure would cause problems for the other applications.