This could very well be a non issue, but worth considering in a troubleshooting brainstorm.
If you have a MicroSD card installed, and the camera is set to save data to it it could be a potential hurdle.
If you have an older or slower card, a card that is full or failing, or not seated properly it could be failing a status check and potentially force closing the camera.
Or the storage file system could have been changed or broken. Backing up the photo and video files and starting with a fresh clean storage folder and gallery could help - adding your backed up files back after it is reconfigured could possibly help.
It should warn you or default back to internal memory if the MicroSD is failing, but if not you could manually set the camera to save to internal memory and possibly eliminate a significant external variable
Filing a support ticket with HTC could be informative, especially if they are aware of a carrier that broke the camera software in the most recent update and plan to fix it in a future maintenance update.