On a brand new Windows Server 2003/Office 2003 installation, I attempted to re-run the Office 2003 installer to change some options. Instead, I received an error message with error code 1327, complaining about X:\ being an invalid drive.

But I don't have a drive X:! I never did! My CD-ROM perhaps wasn't drive F: when I did the original installation, but it definitely wasn't X: either! And the target drive for the installation is C:. What could be wrong?

Naive attempts to create a drive X: and either map the installation CD or a temporary directory to it did not resolve the problem. Reading the logs, however, revealed the underlying cause: at the time I did the original install, I did have a drive X:, which the Office Installer used as a temporary caching drive.

So what can I do now? None of the recommendations in the Microsoft Knowledge Base were of any use. However, I found a solution by editing the Registry. Under the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\11.0\Delivery, you can find one or more subkeys containing GUIDs. Under each of these subkeys, there is a string value by the name of LocalCacheDrive. In my case, the string value in each case was 'X', which I changed to 'T' (the partition where my temporary files reside.) After that, the Office installer worked correctly.


The above was written in February, 2004. It is now September, and I ran into trouble with the new Office Service Pack 1: it refused to install. I suspect that the root of the problem was the same; a Microsoft Knowledge Base article did suggest that if you install Office from a network location and then attempt to change or upgrade it using a CD-ROM, it will fail. The recommended solution was an uninstall/reinstall, which worked in my case.

Note that if you run into the 1327 problem, you cannot even uninstall Office! So you still need to make the change in the Registry, but I recommend that afterwards, you completely uninstall and reinstall Office, to avoid any problems later on.