Sometimes it is inevitable that the PC blocks; the problem is when there is no way of being able to shut down or restart the machine to get things going again. In these cases you need a tool like Ozemail Rebooter.
With Ozemail Rebooter you have a tiny utility (just 5KB) that requires no installation and which, on being run, forces the PC to restart. It doesn`t matter what type of block it is, as the PC will be shut down and restarted quickly and immediately.
Also, Ozemail Rebooter is totally free.