Camera app on HTC Sensation keeps crashing
Go to Settings &rarr; Apps &rarr; Manage Apps, find your Camera app, and look if you can "Clear Cache" and/or "Clear Data"; maybe something got messed up there.

If that doesn't help, try clearing the apps Dalvik Cache (you are rooted, so you can do that): ROM Toolbox Lite and DroidTweaker (ROOT) are two helpful apps for that. Same background as above: Sometimes something gets messed up here.

A very last resort would be a factory reset -- but keep in mind that this would also wipe all your self-installed apps plus data of all apps, so have a good backup of all your data available (hint for that: Titanium Backup ★ root, which also offers a "Dalvik Cleaner" feature -- but as far as I remember this only removes "orphaned" entries (from apps you uninstalled, and the like).