Problem Transferring Pictures from Vista Computer

Hi!  I have a new Dell XPS notebook with Vista Home Premium and a Dell
desktop with Windows XP SP2 all updated.  I am running into what seems like a
weird problem and I'm not sure if it's a problem with Vista or the memory
card reader on the notebook.  Here's the details:  I used my memory card
reader on the notebook to pull pictures from my camera's memory card.  Since
my computers are networked and my desktop is where I store my pictures, I
moved the pictures directly from the memory card onto my XP desktop.  Well,
today when I went in to view and manipulate the pictures, I found that they
don't seem to exist.  There is a thumbnail of the picture in the folder, but
the actual picture will not open in Windows picture viewer and when I look at
the properties tab, the summary section says that properties are unavailable
for the selected source.  Basically I have lost these pictures because no
other programs recognize them or will open them.
Any ideas?  Is it a problem with the transfer from my memory card reader
itself, or is this a Vista to XP problem?
I did have this happen once before with pictures back in June, but I can't
remember how I tried to transfer them.  I think back then I transferred them
from the memory card reader onto the Vista notebook and then later moved them
across the network onto my XP desktop, but I don't remember for sure.

Just wanted to post some further information to see if anyone else has

Just wanted to post some further information to see if anyone else has
experienced this--we did some further testing and now cannot get the problem
to replicate.  The problem I have is, how to know if there was something
specific we did to cause the pictures to be bad in the first place.  We took
new pictures and tried various techniques for transferring them--ie.
copy/paste from memory card window to network folder, "move the file", "copy
the file", etc. and now we can't seem to replicate.  But the problem did
happen and we can't find any difference between the pictures taken today and
the pictures that ended up not transferring properly.  I'm rambling, but
hopefully have enough here for someone to understand.  THanks!

I have a similar problem transferring photos from Vista to XP.

I have a similar problem transferring photos from Vista to XP. If I use Vista
to copy photos I have downloaded from my camera to XP, they will be readable
until I boot the XP machine. After the boot the photos are corrupted. If I
use XP to get the photos from Vista they stay readable even after a boot.
This problem seems to be corrected after installing Vista public SP1 RC
refresh. SP1 though introduced a new problem for me in that some photos are
chopped up during download from the camera to the PC. I hope that problem
will be solved in the final release of Vista SP1. My camera is a Canon Rebel
XT connected via USB. I have tried a reader with the CF card and I still get
chopped up photos after installing SP1 RC refresh. I have tested this on a
clean install of Vista with no other applications installed.