When installing LibO 3.5.0 Beta 2 I saw the message 'Please exit LOdev 3.5 and the LOdev 3.5 Quickstarter before you continue ...' although I have never installed any version of LibO on this computer. Presumably it was really referring to the fact that OOo was running. It seems that the message should not refer to a specific version of LibO, and should accommodate the possibility that it's OOo that needs to be closed.
http://opengrok.libreoffice.org/xref/core/instsetoo_native/inc_openoffice/windows/msi_languages/CustomAc.ulf#11 Do you have a suggestion for the actual new text?
What about: "Please exit LibreOffice/OpenOffice.org and the corresponding Quickstarter before you continue. If you are using a multi-user system, also make sure that no other user has LibreOffice or OpenOffice.org open." When I was doing this yesterday, after I exited from OOo and then clicked OK in this dialogue box, the installation terminated and I had to start it again. Perhaps this message should say 'and then restart the installation' rather than 'before you continue'?
Andras Timar committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=a4ae955534ccc449ddf55fe1b5e5a25065af2ecd fdo#44717 More helpful text when installer detects a running soffice.bin
I added Fix submitter as assignee because this will ease queries and bug tracking.
*** Bug 50397 has been marked as a duplicate of this bug. ***