I’m trying to install Joomla 2.5 via the one-click-install. I had a 1.5 site up, which has been taken down and all the files on the domain have been erased. However, when I go to install it says Joomla is already installed on this domain? I do have other domains that Joomla is installed on running, but not this one now.
Having just gone through a similar problem it’s probably because you haven’t removed the previous Joomla install from the list of installed packages.
Go to the One Click Install page, then select the “Manage Installed Applications” option, find the listing for the domain that you’re trying to run the install on, and select the “Remove from list” option (failing that, use the “Delete all files” option) - that should do the trick