First, is this similar tot he problem you are having?
http://androidforums.com/droid-x-al...you-can-get-2-3-15-w-o-ota-2.html#post1674577
My screenshot shows the LPP widget showing no calendars available.
When I would open the calendar app, and then go to agenda, it would force close.
To backup your apps you can use Titanium Backup (worth purchasing) This backs up apps and their data. I also use appbrain, this just creates a list of apps you have installed and re-installs them. Since I heard sometimes it's better to start fresh, I used appbrain this time around, except for a few apps I restored with titanium backup (such as things I had not purchased from the market). It took some time. Theres another program called mybackup that will do the job as well and there is a free tiral available in the market.
In Titanium backup you can do a batch process, and backup all System and/user apps. I didn't want to restore whatever it was causing a problem, which is likely the system calendar apps (so I would not restore these once you have wiped). In fact I did not restore ANY system apps or data because I wanted a clean start with those to avoid causing the problem again.
Also, be sure google is syncing your contacts, I would assume it is since you have the latest tranquility.