cant map network drive

I am trying to map a network drive on a pc running Windows XP Pro 32-bit.
The network share I want to map is shared out on a Windows XP pro 64-bit
machine. Both are running the latest service pack. On the x64 box I have
shared out the C drive which I have successfully mapped as a network drive
on the 32bit box. What I CANT do is map the D drive from the x64 machine to
the 32bit machine. Just to give you a little more BG info on the 32bit
machine, it already has a couple of mapped drives in addition to the one
from the x64 machine. The local disk is a 2TB disk split into several
smaller partitions.

The "D" drive on the 64 bit box is a Lacie 4TB(4 x 1TB disk drives) USB RAID
array. I first tried setting this up as RAID 10 which would keep it under
the 2TB 32bit MBR limit. This volume appeared in x64 as a 1.8TB MBR
partition. I setup up for sharing and when I tried to map it on the 32bit
box I would get the error:

"The mappped network drive could not be created because the following error
has occured: Not enough server storage available to process this command"

OK. So then I went back to the 64 bit box and sliced up the volume and made
a 500GB partition. Tried to map again on the 32bit machine and got the same
error.

OK. So I googled the error. In one thread there was a resolution to the
exact problem I am having and which I tried but turned out unsuccesfull.
Basically the solution was to go into the registry and madify the
IPRStackSize key, which in my case the 32bit machine did not have that
particular key-so I created it. But like I said- It did not work.

OK. The only other thread I saw related to my particular error message said
to try updating the NIC drivers. I have not done that yet. Before I do I
wanted to get some ideas from the newsgroup. I am thinking I should (A) Free
up some HD space on the 32bit machine and/or (B)create a smaller partition
( 500GB)on the x64machine and try again.

Any other ideas?

Just FYI I plan on getting GPT mounter for the 32bit box so I can
re-configure the RAID as a RAID 5 and go beyond the 2TB limitation. That
would yeild about a 3 TB volume which hopefully I can map to the 32bit
machine, or just get another RAID box if I cant solve the mapping problem.
Has anyone had any expierence with the GPT mounter software?