Trying to set a new drive letter for your virual drive and this error shows up?

Control Panel >> Device Manager
The drive will be under other devices
Right mouseclick on the drive >> Update driver software
Point to C:\Windows\System32

And you driver for your virtual drive will install and now its possible to set new drive letter

If you have security patch 896358 installed or you have Windows 2003 SP1 it is possible that you cannot view .chm files on a remote share.
To fix it you should make a .reg file with the following content:
REGEDIT4
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp]
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions]
“MaxAllowedZone”=dword:00000002
Run it and viola you should see your content again from a remote share.