Long story, but neccessary to understand full problem.

Problem: Unable to access shared drive on network.

I can see any shared folder on the network, but when I attempt to access them , I get an error message. The gist of the message has the message "not enough server storage is available to process this command". I searched that error message and got the instructions to use regedit to modify the IRPStackSize parameters. After following those instructions, when I checked my other computer, not only could I not access the network drive, computer 1 disappeared completely from the network.

By the way, there was NO entry in registry for IRPStackSize, so I followed the instructions to add it. When I rebooted, I got a message that I couldn't catch in time about unable to communicate with address referenced at.... click OK to continue or cancel to debug (the computer rebooted before I could jot it down....

Now a little history....
I had to replace the power supply on computer one. No problems....
while waiting for said power supply, I disconnected network drive, and connected it to computer 2. I was then able to access the drive as a local drive on computer 2.
After changing power supply on computer 1, (first big screw up ahead), I didn't see that I had a flash drive in on of the USB ports, so the drive that was previously labeled G: became H:, which invalidated a lot of my shortcuts etc, on computer one.
At the time I didn't know how to change the drive letters (found out later, and switched back, but that was several mistakes down the line.)

Well, I ran across CCleaner which cleans unnecessary files from your computer, it did wonderfully, and then I saw that it had a registry fix as well (uh oh...)
Well, I ran the registry fix, and as expected got a gazillion errors, mostly relating to the mislabeled drive....I could've sworn I created a backup of it, but I can't seem to find it, nor do I know how to reload it.

My suspicion is that when I deleted all of those erroneous registry entries, i inadvertently deleted the IRPStackSize entry, and another entry that relates to it, which I have no idea what it is....

So, after deleting the IRPStackSize entry, I can again see computer one and the shared drive on the network, but cannot access them.
(Back where I started)
Okay, last but not least: Computer one is XP (SP2), computer 2 is Vista & computer 3, is Windows 7 ultimate (YES I GOT AN ALIEN M11X, Whoo hooo!!)
I am certain that the problem is on computer one, and pretty certain it is a missing registry entry that communicates with IRPStackSize....but I don't know what it is....I did install the app that lets Vista and Windows 7 communicate with XP...

 

I would recommend running a repair install of XP to rebuild the registry. Also there is no app needed for Windows Vista and 7 to communicate with XP so I suggest you uninstall it in case it is the problem.