I'm getting the following error when installing the 4.03 SP3 executables on a Windows Vista workstation.
Error 1327.Invalid Drive: u:\
U:\ is a perfectly valid network mapped drive that the user has permissions to.
I use a scripting software called Desktop Authority, made by Scriptlogic which re-directs the 'my documents' folder, desktop icons, and internet explorer favorites to a mapped drive (so they get backed up).
I'm almost positive this software is changing registry keys, I can change them back per the following article, but I'm sure the next time the user logs in, it will re-break them.
http://support.microsoft.com/kb/327763