screen flashes of command boxes with application in c in windows

We build a dynamic library in c in windows using Microsoft Visual Studio 2008. This library is used by an GUI Application. This library has many dos commands.When we run the GUI application screen flashes of command boxes can be seen. We need to avoid this screen flashes.

sample dos command code we use in dynamic library.

system("ver 2>nul > OS_version_file");

Is there any method to avoid screen flashes.