iphoto keeps freezing up and events do not show photos, missing photos, constant crashes

I have a recurring issue that is causing major headaches. It involves iPhoto (9.4.3 the latest version currently) and I noticed that photos and videos I had imported seemed to be missing. I started looking deeper and there were photos and specifically videos that I just could not find. I had synced them from my iphone via a cable sync. What is odd is I found some of them in an event farther in on my events list but that is when more probalems started occuring. iPhoto froze up on me while I was working with the photos. Now when I open iPhoto I have 3 events that have photos and videos in them but the event do not have a visible photo, instead they show a grey icon with palm trees on it. If I go inside one of these events I initially see photos and videos that I took but if I try to work with them, view them, move them, or split them iPhoto becomes unresponsive and I have to force quit or wait for it to crash. This is frustrating because I can't really use iphoto lately it always seems to crash and I don't know all the causes for that. I also feel bummed because I don't know if these photos will be lost or if some of the other photos are lost. I don't know what to do. I tried verifying my disk and permissions with DU and fixed a few issues there but that did not do anything to reslove this issue.