應該是是已經有個cl.exe執行，還沒退出，再要編譯執行，就會出現這樣。解決方法：

4. 重新設定“Excutable Fils、Include Files、 Library Files、Source Files”的路徑。

如果你是按照初始路徑安裝vc6.0的，路徑應為： executatble files: C:\Program Files\Microsoft Visual Studio\Common\MSDev98\Bin C:\Program Files\Microsoft Visual Studio\VC98\BIN C:\Program Files\Microsoft Visual Studio\Common\TOOLS C:\Program Files\Microsoft Visual Studio\Common\TOOLS\WINNT include files: C:\Program Files\Microsoft Visual Studio\VC98\INCLUDE C:\Program Files\Microsoft Visual Studio\VC98\MFC\INCLUDE C:\Program Files\Microsoft Visual Studio\VC98\ATL\INCLUDE library files: C:\Program Files\Microsoft Visual Studio\VC98\LIB C:\Program Files\Microsoft Visual Studio\VC98\MFC\LIB source files: C:\Program Files\Microsoft Visual Studio\VC98\MFC\SRC C:\Program Files\Microsoft Visual Studio\VC98\MFC\INCLUDE C:\Program Files\Microsoft Visual Studio\VC98\ATL\INCLUDE C:\Program Files\Microsoft Visual Studio\VC98\CRT\SRC