Same problem with me. It happened after I changed my web hosting. A quick check reveales that I am having GD library error where it says I am exhausting the memory alloctated. The weird thing was that this provider allocated 32MB of memory, twice the 16MB that my old hosting gave me.
I found out the problem. Seems that when I used a browser that logged in my site for the first time, it will default change to visual view for edit. somehow the visual view changed my coding and added some <p> tags WITHOUT closing it. deleting these tags solved the problems
