Thank you for contacting us, and I'm sorry for the issue you are experiencing. I'm not exactly sure what's happening here, but it looks like you are using Dropbox syncing, so it might be that the sync file has become corrupted in some way. On your PC, can you go to mSecure's Sync Settings and try turning off syncing. After you turn syncing off, go ahead and open mSecure on your iOS devices to see if the app still crashes, and let me know the results.
It's good that we now know what's causing the problem. I think if you simply delete the sync file stored in your Dropbox account, that should take care of the problem. It will be recreated, and then any bad data that may have been causing the crashing should be removed.
To delete the sync file, please follow the instructions below:
After that file is deleted, go ahead and open mSecure on your main device so that the sync file gets recreated, and then open mSecure on your other devices. Does mSecure crash on your iOS devices still?