From: Sawyer on

What a nightmare it was trying to get SP2 installed on my mailbox server, i
had no problems installing sp2 on my HUB and CAS servers, but ran into
multiple issues installing the sp on my mailbox server. All servers are
running Windows 2008 sp2. When attempting to install sp2 on the mailbox
server the first issue I ran into was the install errored out with "Setup
previously failed while performing the action "install". You cannot resume
setup by performing the action "BuildtoBuildUpgrade" After getting this i
googled it and found I followed the
procedure in the blog, and after this i was able to run the install. After
re running the install for a second time, i then got another error regarding
the admin tools not being current, so off to google again and i found
and it pretty much matched the error i was getting spot on. I followed the
procedures in this article and re ran setup, but kept running into the same
issue with "admin tools not being current" I also had to delete the
watermark and regsitry keys before trying to launch the sp2 install, but
every time i did this the install would fail and when i would look in the
ESM i would see a "phantom" storage group that i dont use and when i looked
in adsiedit sure enough i would see this bogus storage group, this really
confused me, everytime i deleted the bogus storage group deleted the
registry keys and reran setup, the bogus storage groups would get created
again, this really confused the heck out of me. Anyways my mailbox server is
in this funky version it doesnt know if its at a sp2 or sp1 level, the
service are started and the stores are mounted and users can connect, but
this configuration isnt good