Having errors relating to the ACP and MCP

I'm using IPB 4.0.4. 

When inside the ACP, I receive this error: 

http://i.imgur.com/z91CncQ.png

I can try to navigate around the ACP, but I am met with the same error message when I try to access member accounts, or make changes to the forum.

When in the MCP, I receive this error:  

I can't do anything at all in here.

Help would be nice, thanks.