Cannot add posts or pages after host change

Hi there,

having a weird issue with a client’s site. We did a host transfer and everything has gone smoothly. However, when attempting to add a new page or post, WordPress simply goes to a basic page displaying the following message:

Thank you for creating with WordPress. | Documentation | Feedback

Version 3.1.3

Has anyone else had this issue? I’m guessing there is some sort of file missing. Does anyone know which core files are used to create new posts and pages?

Thanks in advance.