[General] White screen of death after posting

[Toledo]

Basicly, I get a white screen of death after I post a new post.

This happens a lot of times but not always.

This is the URL that comes up when it's a white screen.

http://www.domain.com/newreply.php?tid=2286&processed=1

And if I refresh it it says.

Cannot upload the file - Too big for PHP post_max_size directory. Please press the button.

(Translated from Swedish by myself)

Any ideas?