Exchange 2010 (& Service Pack) Setup: A Restart from a Previous Installation is Pending

Exchange 2010 or Exchange 2010 Service Pack fails on Exchange Analyzer on checking pre-requisites. This should be easy to resolve. If you are seeing this same error after reboot, there must be orphaned registry values left from previous setup files. Check and fix the following two registry keys and setup should continue normally. 

To remove an orphaned UpdateExeVolatile registry key value

1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

2. Navigate to HKLM\SOFTWARE\Microsoft\Updates\

3. In the right navigation pane, double-click the UpdateExeVolatile key.

4. Configure the key with a value of 0

5. Close Registry Editor.

To delete the orphaned PendingFileRenameOperations registry key

1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

2. Navigate to HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\

3. In the right navigation pane, right-click the PendingFileRenameOperations key and select Delete.

4. Close Registry Editor.

I found this info at http://technet.microsoft.com/en-us/library/cc164360(v=EXCHG.80).aspx.