This error was such an odd one, I thought I'd share it.. We've been creating MSI packages using Wise, and they have been running very well on pretty much all computers. So imagine my surprise when I get an email from a guy at the Norweigan it department saying that when he tries to install the package he gets an "Error 1327. Invalid drive h:\" message.

He was logging on as domain admin on a setup where they have roaming profiles (i.e. the My Documents folder etc is stored on the network). After some investigation, he found that if he changed the registry key for My Documents (Hkey_Current_user\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folder\Personal) to use the complete UNC path instead of "h:\" as was used before, it all worked without any problems.

First of all, we don't install anything to My Documents or anything else that should be user related. But apparently, the installation uses that path for storing temporary files or something.

Anyway, just for the heck of it, he tried changing the registry setting to the complete UNC path instead (i.e. \\servername\etc\etc). And voila, the installation succeeded!

It turns out that the server he was using was a Win 2000 instance on MS Virtual Server. After a LOT of searching, I found a couple of articles that mentioned a similar error: MS KB 255582. AppDeploy.com FAQ To sum them up, MSI packages that are installed remotely via Terminal Services on a Win2000 box (and I guess that Virtual Server uses the same functionality) cannot use mapped drives because they are running in a different context (the Windows Installer service is running as a service in the console session , not in the session of the remote user).

The solution.. Well, either use UNC names in the registry or upgrade to Windows XP or 2003 where this problem is supposed to be solved..!