@Anonymous wrote:
I tried to add some hatch patterns to the existing library, ... & somethings gone wrong, ....
If you added pattern definitions to the end of AutoCAD's file, make sure you ended up with a blank line at the end. That is, if in the file in a plain-text editor such as Notepad, when you press Ctrl+End to get to the very end of the file, you should be on an empty line at the bottom, not at the end of a last line containing code. If the latter, hit Enter to get a blank line at the end, save the file, and try again. [You may need to close and re-open the drawing, or get into another one, or possibly even re-start AutoCAD, to get it to re-load the file.]
Some of your messages are about its not being able to find the acadiso.pat file. Try [in a drawing] typing (findfile "acadiso.pat") to see whether it's in a location in the Support File Search Path list [OPTIONS command, Files tab].
Kent Cooper, AIA