Tip from Matt Carlson on the sbs2k list – installing update rollups from Exchange are slow going…mainly because there’s a .net process doing regeneration stuff…and it’s slowwwwww.
If you go into IE Options: Advanced: Check for publisher’s certificate revocation – Disable this (uncheck) and the update roll-up will go MUCH quicker
Also keep in mind that it’s normal procedure for any Exchange update to go in and disable Exchange services during an update. Sometimes it hiccups at the end and forgets to turn them back on.
Try putting the services back to normal – check out this blog post – and see if everything is okay.