>While compiling the project (for simplicity, I just selected a "rebuild project"; all other options are unchecked), I get a message "error reading file". Not knowing which file caused this, I created a new project; the "error reading file" appeared for one particular class library, more specifically, a file called vfxform.vct (part of the Visual Extend framework). According to the help, the error message means that:
>
>"The operating system returned an error while Visual FoxPro was attempting to read the specified file."
>
>However, I can open the class library, and make a duplicate on disk. What might cause this?
>
>I also checked whether the file isn't read-only.
>
>TIA,
>
>Hilmar.

Did you try closing VFP and re-building the project after re-opening it? It it doesn't help, I suggest re-booting the machine. If it doesn't help either, then getting this library from the most recent backup.