Debug | Kernel Connection | Resynchronize
Point to Kernel Connection and then click Resynchronize on the Debug menu to cause the debugger to try to reestablish a kernel debugging connection with the target computer.
This command is equivalent to pressing CTRL+ALT+R. (You can also press CTRL+R in KD.)
Use this command if the target is not responding.
For more information about reestablishing contact with the target, see Synchronizing with the Target Computer.