Access is Denied (from Local Disk Manager)

I am partitioning my C drive so I can install Windows Pro as a duel boot to

the pre-installed Windows Vista Home Premium 6.0 )build 6001: Service Pack

1) My instructions says that I am to select "Shrink Volume" in Disk

Management. It starts to do that then I get a box that drops down that says,

"Local Disk Manager" at the top, and below it says "Access is Denied". How

do I get past this to shrink the volume?

G@ry