IRPStackSize again...

This parameter has bothered me again.
I've installed a SQL server 2005 clustered environment that required some named instances. Everything went fine till I had to define the location of the data files in the selected cluster group.

I got the error 'These is not enough disk space on the destination disk for the current SQL server data files [...]'. It should have been 'There is...', but then, at Microsoft, even writing correct English is difficult.
This error is not correct since the disk I specified had 200GB free disk space and I could create files using the windows explorer.

The problem was caused by a too low value of the IRPStackSize. What is mentioned here is total rubbish.
Increasing the value from 16 to 20 (decimal values) solved the problem for all SQL instances I had to install.
The parameter is located in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer
\Parameters