400 BAD Request

[eddyndm]

Hey guys,ive been adding content and all of a sudden i recieve this error when trying to add content:

Bad Request

Your browser sent a request that this server could not understand.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Details : CMSMS Version : 1.9.4.2

Clean install, not tampered with, was working before i added various pictures to the content, then the error started.

Any ideas?

Many thanks