I can open my project from the "File" dialog, but if I try double-clicking the ISE file I get:
"The project ... you are attempting to open does not have write permissions and therefore cannot be opened in Project Navigator.
This could have occured if the project was attempted to be opened in an earlier version of ISE software.
In order to open the project, you must either change the permissions of the project file or make a writable copy of the project file."
Unfortunately the eroor message doesn't tell me how to do either of these things, and I can't find anything on this in the help.