I have CS4, PC. Upgrading to ACR 5.5. First it tells me I do not have 64 bit which is correct. Next it tells me that Bridge 64 bit is open, close to continue. Reboot, reset, same results. Can't shut down something I don't have running but the upgrade then quits till I do.?????
Check in TaskManager's Process list to see if Bridge.exe is loaded even though you haven't started it, manually. If you see it, use End Process to stop it prior to running the upgrade.
You probably accidentally turned on 'run Bridge at startup.'
On the bottom right of your Windows, there is a taskbar/notification area, you should find "Br" icon, exit Bridge from there or you could bring up Windows Task Manager, and end "Bridge.exe" process
Thanks for your answer, didn't know it stayed "active" even after I shut it down.