informix error 461 -- File Open Error

Hello all-- I'm getting an error 461 when I try to run isql on a database that was last accessed about two weeks ago. The engine appears to be fine (it is in the nine online state). The only 3 chunks the database knows about are cooked files and I've tried 660 (informix.informix) and 4755 (informix.informix) as permissions levels. As the most obvious files seem to be okay (permissions-wise) and the other suggestions finderr gave--disk space or num_open_files--don't seem to apply, I am at a standstill. Does anyone know if there is a way I can get more information from the error, i.e. what name/inode of the file it can't open? TIA for anyone who responds. BTW: online 5.0. --Brad