This creates a maintenance problem, particularly if the system files need to be replaced. Many organizations have begun locking down the Windows and System directories, in an effort to reduce maintenance costs. This was how things were done in the Win 3.1 days. The order in which directories appear on the path becomes important. The system spends a great deal of time searching directories that are never used by the application.
Installation programs require re-boots for the path changes to take effect.
Microsoft has offered a solution to all these problems. With an App Path registry entry, the system will load DLLs in the following order. The directories listed in the App Path registry key The directory where the executable module for the current process is located. The current directory. The Windows system directory.