private idaho

I am trying to run Private Idaho. I tried the 2.1 version as well as the new beta version. I have all the files in the same directory as PGP. When I create a message and select clear sign it spawns a dos box that is all black with the cursor in the top left corner. If I hit return it closes the box and gives the following message: File not found in the sign routine, couldn't create output file. Any ideas on what might cause this or pointers to additional information would be welcome. Steven Ryan sryan@reading.com