Maximum of page-locked memory?

Hi all,

I am running a WindowsXP-64bit box with 8GB of RAM. And it seems that I can allocate a maximum of 1GB of page-locked memory using cudaMallocHost or cudaHostAlloc with the cudaHostAllocDefault flag.
What is the reason of the limit and how can I increase it?

Thanks in advance.

Are you running 2.2 or 2.3?

I am running 2.3