Normally, yes. It means the computer is stuck in a loop, and probably won't come out of it.
Try downloading iPhoto Library Manager (get it here
), and opening it. From the File menu, choose the Rebuild library option, and remember where you saved it. Once it's finished, open iPhoto while holding the Option key, and select the Choose Library option.
Navigate to the Rebuilt library you just created and try opening it.
If that doesn't work, as a last resort, go back into iPhoto Library Manager. From the File menu, select the Extract Photos option. That will pull all your raw photos out, so you can at least have them in the new version of iPhoto.
You'll lose some settings and organization, but you'll have your photos.