Problems solved, hooked up a 500KHz ceramic resonator and set the fuses back to 16Mhz ext. and everything is back to normal.
hiduino:
...USBasp firmware can be upgraded to support lower speeds for AVRs running at 128KHz. In addition it does have the hardware jumper (J3) support for slow sck clock, but only if you update the firmware. I have one of those USBasp programmers and have tried this, so I know it works. But I think you have a bigger problem with your fuse selection.
Would be great with the updated firmware, I've been running with the 2011-05-28 all the time but people keeps saying that there is an update to it. I would be very happy if you could give me the newer one!
I've also read that the J3 jumper is obsolete for the newer updates like 2011-05-28, but you mean that it is first in the later updates it is used?
Cheers!