I was upgrading SQL server 2008 to 2008 R2, the installtion stops with error "SQL Server 2005 Express Tools in installed" !! please uninstall, but unfortunately I don't have that!! and can't find it under the list of installed programs in the control panel!
Tried the skip check flag "/skiprules=Sql2005SsmsExpressFacet" with no use !!
I took a backup of the whole registry, and removed the whole "Registry Key 90" folder!
HKEY_LOCAL_MACHINE > Software > Microsoft > Microsoft SQL Server > 90