I just found a solution to a problem that was getting on my nerves for quite a time: I am using three computers, all WinXP Pro. They are all connected in one simple network and I don’t use much more than some folders to copy files from here to there. It worked fine for a long time but one day I couldn’t connect to anyone of the computers anymore. I am pretty sure I didn’t change a thing – it just happened. I browsed a lot (and I mean a lot) of websites that are dedicated to this problem. Most of them say (text copied from here):

1. Start the registry editor (e.g., regedit.exe).
2. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services \lanmanserver\parameters.
3. Double-click IRPStackSize (or if this registry setting does not exist, create it of type DWORD and ensure the case is correct).
4. Change the base to decimal, set the value to the default value for your OS, and click OK.
5. Reboot the computer or restart the “Server service”.

It did not work for me.

But I found the solution two minutes ago one on single German web site: When changing the value of IRPStackSize DON’T CHANGE TO DECIMAL. Change to (or leave it at) hex!.

Hex 30 (= Dec 48) was enough for me and after a reboot it worked again.

What a bug, MS, please fix it!