Just released 2 NEW hot fixes for 2007 products.
Hotfix - Fatal Error During Save
Hotfix Cut and Paste
The first, very much applies to Civil 3D 2007. Actually, they are the same fix. Which is to download and install the latest version of acdb17.dll.
If your version is less than 184.108.40.206 you need to download and apply the hotfix.
How do you check the version? Find the file in the program root directory, right click and choose Properties. In the acdb17.dll Properties dialog box select the Version tab. The file version will be specified.
I ultimately applied the fix three times:
AutoCAD 2007 (I have a separate install for this program)
Civil 3D 2007 (not needed if SP1 installed)
Land Desktop 2007