Why the bulb randomly will stop lighting up in the middle of a treatment?

First, you're using the wrong Preset - JW-Spooky Central is for frequencies higher than 100,000Hz. You need to use the JW-Spooky Central Low Frequencies Preset where some or all of a Program's frequencies are lower than 100,000Hz.

Please see page 10 of the current Spooky Central User's Guide:
http://www.spooky2.com/downloadsPage/index.html

Second, from scrutinising your photos, it appears you're not using either Dick Ring BNC cables to connect the generator to Spooky Central, or a Dick Ring USB cable to connect the generator to the PC. A Dick Ring cable is one that's coiled multiple times around a heavy metal ring. This ring must be left in place, and the cables should not be uncoiled.

These suppress EM interference from the plasma tube which can lock up the generator or the PC, or both. Currently, two Dick Ring BNC cables and one Dick Ring USB cable are supplied with every Spooky Central. Failing that, the only answer is to place the generator and PC a lot further away from the tube, perhaps on the opposite side of the main rig. You will likely have to source longer cables for this.

For more details, please check the link:
http://www.spooky2.com/forums/viewtopic.php?f=74&t=4727&sid=739f07add2bc9cbeb2e9684eab8f8361