Like an idiot, I upgraded to 3.3 and installed a new theme at the same time (Prophoto4). Now, when I'm administering the site - trying to create a new post, adjust my widgets, I get memory allocation errors and blank screens. I also get publish failures.
When I disable W3 Total Cache, these errors go away.
My site runs fine from a consumers perspective whether the plugin is enabled or not enabled, its the admin functions that stop working. Most frustrating is it's not consistent.
I've spent a bunch of time turning other plugins on and off but only turning W3 Total Cache off makes the admin problem go away.