I have a PC running Windows Vista so what I had to do was in iTunes make sure that all my photos were SYNC'd with my pictures directory. After that when I was sure that I had all the photos that were on my iPhone in my windows pictures directories then I deleted all my pictures off of my iPhone. In order to do this once you plug your iPhone into your computer via the 30 pin dock connector cable, and after the computer recognizes your iPhone, a window will pop up in Windows that shows your device. iOs will allow you to open up a file folder that contains your photos.
Note: there may be several file folders depending on the library size of your pictures and if you have photo stream enabled. In my case I had four folders and these folders or a combination of numbers and letters. These folder names are randomly generated through iOS but just be aware that these folders contain your photos and videos. I know that one folder was just my photo stream because I did not have very many pictures, and two folders had my entire photo library and camera roll in them and another folder had just my videos in it.
The process is pretty simple: once I open these folders, I highlighted all my pictures and deleted them. Once they were deleted off the phone then I went into the iTunes "summary" page for my iPhone. I then went to the "photos" tab and I made sure that the box was checked to sync my photos. In my case I don't have my entire photo library on my phone so I have selected folders button checked. Then I just SYNC'd my phone again. It didn't take too long for iTunes to transfer all my photos back to my phone. After this process was complete I checked all my photos and tried to crop them and had no problems. I also did some screen captures on my phone by pressing the sleep/wake button and the home button at the same time. Again I tried to crop photos and had no problem.
So what I believe with the expert advice from Adam Christiansen of the Mac cast podcast was that I had a corrupt photo file or corrupt metadata from a photo file. So what this was doing was causing a system crash and reboot in iOS. I was able to verify this in my diagnostic files on my iPhone in the settings / general / about / diagnostics and usage / diagnostics and usage data TABS.
I HOPE THIS HELPS YOU AS IT ALLEVIATED MY PROBLEM. I HAVEN'T HAD ANYMORE PROBLEMS WITH THIS ISSUE AND WHAT I'VE DESCRIBED ABOVE IS A WAY TO DO IT WITHOUT RESTORING YOUR ENTIRE IPHONE. IF YOU STILL HAVE PROBLEMS AFTER DOING THIS THEN YOU HAVE ANOTHER PROBLEM WHICH PROBABLY REQUIRES THAT YOU DO DO A COMPLETE RESTORE OF YOUR IPHONE. BUT BEFORE YOU DO THE RESTORE MAKE SURE THAT YOU BACKUP YOUR IPHONE AND I WOULD SUGGEST DOING THAT TO YOUR COMPUTER AND NOT TO ICLOUD; MY REASON FOR THIS IS THOUGH ICLOUD IS A WAY TO DO IT IT JUST TAKES MORE TIME TO RESTORE FROM A BACKUP VIA ICLOUD AS OPPOSED TO A TETHERED BACKUP VIA THE 30 PIN DOCK CONNECTOR CABLE TO YOUR COMPUTER.