After installing ML yesterday, iphoto will not open.

iPhoto crashes immediately every time. I have updated iphoto to the latest version--supposedly to work with Mountain Lion. My imac is a mid-2007 model and has 4 GB of RAM. I am currently restoring from Time Machine to go back to Lion. Perhaps I shouldn't have been so hasty to install ML. So far, I have restored iphoto from backup (did not help), repaired the permissions (no help), deleted and reinstalled iphoto (no help) and done pretty much everything suggested for earlier OS's. Since I have paid for Mountain Lion, perhaps I will try again in a couple of weeks. Any thoughts on why iphoto crashes? If my iMac is too old to run it successfully, it should have not been on the OK list. I am waiting for the new release of iMac, supposedly in October and was ready to buy in June, had they released the refresh then.