Watchdog has expired. Target detached

Hi,
Im newbie in Net OS+ programing. I have new DIGI Connect ME NET+OS. And Im trying to run samples, but always after random time I recieved this error from JTAG:
Watchdog has expired. Target detached.
Have absolutely no idea whats wrong?!? Some times JTAG alerts me after this message that he measured 8V or more volts.

Jirka