HLdsUpdatetool.exe is not a valid Win32 Application!

Im trying to start up a free garrysmod server (im so cheap) but a pop up screen says

HLdsUpdatetool.exe is not a valid Win32 Application!

And On The Comand Promote says:

hldsupdatetool -command update -game garrysmod -dir C:\srcds
Access is denied.

When I Try Launching The Command (below)
hldsupdatetool -command update -game garrysmod -dir C:\srcds

Info:
Manufacturer: Hewlett-Packard Company
Comand Prompt Version: Microsoft Windows [Version 6.0.6001]
Computer Type: Windows HP
Computer Version: Windows Vista Home Premium
Service 1
I don’t know if this might help:
Memory (RAM) 4.00GB
System type: 64-bit Operating System


Please tell me how to fix this, I Have everything ready for a server.