Error Meldings Freezes, enz

Hi,

I have some problems.
The printer printed 3 min., then freezed.

I put the calbles form the USB directly on another PC, the adapter form the K8200 as far as possible away, I also used the ferrit core.

If i use the printer manuel evrything seems to be ok.

I use Windows 7, Repetier 0.85 on my computer.

The printer starts but remains at 0,0; it goes a little up, but that is it
Then often the error occurs:

Some heaters are still on.
Shall i Disable them
YES // No // Annuler

If I press on any key then the repetier stops and says in the logfile:

Print layer 1 form 125
Error:Checksum mismatch, last line 351
Resend : 352
Error: Line number is not last line number +1, last line 351
Resend : 352

I have also seen this whith another line: 172

Any one an solution??? !!!

Rob