Cannot edit or add new pages

We host a site for someone who uses wp version 2.0.4 for their site. I know it is really outdated, but that is their choice. Anyway, all of sudden they are not able to edit pages and/or add new pages. It was working fine last month when they edited it, but now it will not work. Has anyone heard of an issue like this before?

We checked their server logs and they have plenty of space left on their account so it isn’t like they used up space or anything.

Any help would be greatly appreciated.