I got a strange cautious of Worpress after updating to 3.5.1. When I tried to edit an article, I got an empty content page. Also after switching to the HTML view the content page stayed blank.
In my first troubleshooting attempts I tried to delete my Browser cache and deactivate the WordPress cache. Both without any success.
There are a lot of discussions on the Internet about this problem with different solutions. For me worked to deactivate and reactivate ALL Plug-Ins in WordPress. Till now its works again like it should.
If you have the same Problem try first to deactivate and reactivate all Plug-Ins in WordPress.