Just set the clock option to 128KHz, hit Program, ignore the warning by the STK500 programmer and press OK.
I just don't see why they made this interesting option (at 128Khz divided by 256 it runs at just 500Hz ;) ), but made it so that it disables any further programming. High voltage programming is disabled in STK500 dialog box.
This option is just useless this way. Is this a bug as the tiny2313 still isn't fully developed? I know there is an issue with parallel programming. Anyone know of a way to re-enable programming? There is no mention of it in the datasheet that this clock option disables any further programming.