The installer is going through the automated steps of upgrading you from 758 => 759 =>760. Its a very old installer process that assumed you would be going from one version to the next higher version, to the next hire version. Instead of just from your current version, to the latest version. Im not sure why the original developers ever wrote it that way, since it really "dumps" on any new developer trying to clean up old, outdated and unused files.
I've added your bug report to my notes of things that need to be fixed. For UBB.threads 7.6.1, this will be corrected.
Thank you for this!
