had this error on my iphone when syncing, and found many posts with tother errors, but couldn’t find anyone else with the -50 error. I decided to post this so everyone wouldn’t have to suffer like i did until i solved it. I had downloaded the latest version of itunes, and the latest software for my 4g iphone. this link gave me some information, but didn’t solve my problem. It always blew out when it got to syncing my photos. I finally took all the photo folders out of sync definition. then it synced correctly. Then I added them back, one folder at a time. The first one went. The 2nd one synced, but it gave me the typical error which I had seen every time I synced pictures, telling me that one of the pictures[file name] couldn’t be shown on the iphone. I went and loaded that file. (you can use google desktop or windows search, usually i would find google to be faster, but windows won this time). When i tried to open that file, it was corrupt, and either didn’t display properly, or wouldn’t open at all. I deleted that file. then re synced. It might find another one or not, and I moved through my folders one at a time. I had over 5,000 photos, and over 100 folders, so it was painful. I just kept deleting the files it showed me, and re synced over and over with that just added folder until it synced properly. in a few hours, I had loaded the last folder. victory.
My theory, it was just finding too many of those bad pictures, and blowing out.
I had also noticed that my iphone kept telling me it was too full to add more items,yet it showed 3 gigs avail on the desktop and on the phone. I am convinced that the corrupt images were “pissing” off something in the itunes/iphone.