Anyone know why a login script (in a.d.) that has worked for months and
months would up and not process completely now?

It's merging a .reg (setting a default printer) entry into the HKCU
portion of the registry, and like I said, it's worked for a long time,
just recently quit working properly.

If I try to merge the .reg into the registry manually, I get an error
"Cannot access the registry".

Weird thing is, if I manually change the default printer, then try to
merge that entry, it works just fine.