Hi Andrew,
Have you installed any other new software or updates recently, i.e. shortly before the day on which the Pentax software started giving problems?
Also, if your operating system is Windows have you tried restoring to a point before the Pentax software malfunction? (All Programs>Accessories>System Tools>System Restore).
Bump
Edit: When the run time error comes up it should give an error code. If so, check it against the list of codes
here to get a clue as to what is wrong.