Decomissioning Exchange 2007 - thought I would remove the admin tools for 2007 and leave 2010 tools only. Bam! No more Exchange 2010 admin tools. Can't delete because Programs and Features says it isn't installed. I removed it via WIndows Install Cleanup Tool and started over with a fresh Exchange 2010 SP1 disk and it says "Exchange Server setup encountred an error" before I can get two steps. Now I am pretty much screwed trying to administer from my desktop. All of the related topics are unanswered. Can anyone answer this?SnoBoy

Still trying to get this to work and now have made progress all the way to a new problem. When running Setup, I get to a point then get an error I can't fix: Error: Installing product F:\exchangeserver.msi failed. Fatal error during installation. Error code is 1603. Last error reported by the MSI package is 'Could not open key: UNKNOWN\Components\2E016F08F75B6F848A40D36348D1134D\AE1D439464EB1B8488741FFA028E291C. Verify that you have sufficient access to that key, or contact your support personnel.'. Fatal error during installation Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.ExA12D2D&l=0&cl=cp <-- absolutely no info here!! I can find the registry key, but I can't change the rights on the key, I can't delete the key, I can't take ownership of the key, and finally, if I attempt to use the Replace all child object permissions with inheritable permissions frfom this object, it always fails. It doesn't matter if I use regedit or regedt32, doesn't matter if I run as admininstrator and even subinacl fails to be able to reset the key to allow me to install. I am still stymied.SnoBoy