Clear Run Command Cache

Commands entered in Run dialog box from start menu are automatically cached to be used later for AutoComplete.

One can selectively remove these entries from cached list of instructions.

Go to registry and follow the following path

HKEY_CURRENT_USER/Software/Microsoft/Windows/CurrentVersion/Explorer/RunMRU

and in right pane you will find entries for the Most recently used command in Run box.

Delete the unwanted entries or delete all.