Probably I have messed several delphi versions installations by installing / uninstalling several times (I think I did not follow the order of release). I want to try out Developer Studio 2009 but after installation (althought everything other seems to work fine), when I click The Data Explorer tab nothing is shown on the list. This issue is possibly caused by multiple dbexpress configurations in the registry, but I could not fix it. I get the notion that the uninstaller is of the un-unistaller kind. Registry sucks anyway.
NOTE: OPSYS reinstallation is not an acceptable solution, obviously.