When i try to save in the CK, this comes up:

[IMG]http://i1238.photobucket.com/albums/ff483/Shaveyahead/CKMessage.jpg[/IMG]

Any ideas?

I should note that i've been making a house on this save for months and its only started doing this today. Since i've been making it for months i'd appreciate it if someone could help me solve this, otherwise, months of work would be lost.

Did you set your file as the Active File when you loaded it? Or is the game open when you try to save?

That message indicates the file is in use by another application, probably TESV.exe.

Nope i made sure it was the Active file and i tried saving it with Skyrim closed.