Earlier today, I updated my site to Matrix 2.5.2 and now, I'm getting white screens on all sorts of channel entries that have a Matrix field.
I get white screens inside the CP when I edit an existing entry that has a Matrix field and also when I view that entry on the front-end.
I do not get white screens when I go to publish an entry in a channel with a Matrix field.
To verify that it was, indeed, Matrix causing the issue, I pulled up an entry that did not have a Matrix field. I then added a Matrix field to its channel, and got a white screen. Removing the Matrix field returned the normal, expected behavior.
FWIW, I am using ExpressionEngine v2.5.5 with 64M of memory in PHP.