I went through the procedure outlined, making sure I removed the photos. It worked and now I can open iPhoto no problem.
I don't have any iPhoto plug-ins (that I loaded separately) and am unsure what the problem was (I'd like to know in case it helps someone else further down the line....) I am still finding out what iPhoto can do. I usually resize in Photoshop Elements 2 - it's quick and easy and fuss free. I upload photographs from my desktop to etsy.com. Etsy are like felt.co.nz (another online retailer) where they set limits for image size and make it easy for you to upload. I didn't think iPhoto had a resize facility but I had better check now I can keep it open without the spinning beach ball of doom/death/destruction. You need to be online to upload images to the e-tail sites obviously but as we have always on broadband I assume its on while I am editing photos too.
Marjorie
(off to resolve iTunes which claims it can't open as the library is from a later edition of the software

)