Ok, a BIG thanks to Glenn for his help the last couple days with this. I used his Universal Login Script to do some troubleshooting. On a computer that is working, I can get my U: drive mapped using his script or mine, from either the GPO or the Login Script field in ADUC. However, on a machine that isn't working, neither script works even though I can see them both run. I also added a line to my script right after I map U: to write the contents of the U: drive to a log file ( SHELL "CMD.EXE /C dir u: > %temp%\diru.txt") and the file contains the contents of the drive! But when I get logged on, I do not have a U: drive.

One thing I noticed when I ran Glenn's script from the GPO, on a machine that works, in the group list for the user (same user on both computers), they are in a group called Mandatory Label\Medium Mandatory Level. On the one that doesn't work, the user is in a group called Mandatory Label\High Mandatory Level. I don't know if this is what's causing the issue, but it sure looks suspicious?

I had tried last week to put my logon script in the login script field in ADUC, but that wasn't working either. Thanks again to Glenn, he pointed out to leave out the path here, and that is apparently working now!

So, I have a workaround, but I still think its odd that the way I've been calling the script for years (from a GPO) quit working on certain machines?

Any other thoughts/suggestions are still appreciated.
Thanks,
Mike