I have a feeling this may actually be a bug with the latest build, as I have experienced similar problems. I installed WordPress just last night, and was hit with a 500 Internal Server Error while creating some nested pages.
Thing is; Unlike Fotokunstner, I hadn't touched my installation with any kind of editor prior to the error, and the rest of my website was working just fine. Only the WordPress blog was bugged over.
I simply just left it for the night and went to bed. It was working perfectly when I woke up, until a couple of hours ago. Went to make some pages again, and I was hit with these two:
Fatal error: Allowed memory size of 8388608 bytes
exhausted (tried to allocate 30720 bytes) in
/home/chicagol/public_html/index/wp-includes/widgets.php
on line 210
Fatal error: Allowed memory size of 8388608 bytes
exhausted (tried to allocate 7680 bytes) in
/home/chicagol/public_html/index/wp-includes/widgets.php
on line 260
Only one is shown at a time, but the error alternates between the two.
My blog is over here.
Funnily enough, it's reassuring to know that I'm not the only person who has experienced this error.