Why are some entry detail views empty in the control panel?
That error isn't a Craft or PHP error, it's coming from older versions of xDebug.

It can happen on more complicated pages (lots of fields, tabs, etc.), but you can get around it by adjusting the xdebug.max_nesting_level to something higher than the default 100 or to upgrade xDebug to 2.3+, which has changed to the default value to 256.

Note that you don't have to have an active debug session going on in order to run into this, you just have to have the xDebug extension installed.