I chose the same tag for this problem as one below in an attempt to keep the dialogue open on this issue.  I am experiencing the same thing with my Spider 212 150w as Blooztonez.  It shuts off and on at random.  It seems that Blooztonez question as to weather or not the services centers have been notified of an on-going problem with the DSP were never addressed.  Other than this GLAIRING problem, the amp is great!  I have had the amp for less than 2 weeks now.  The first time it randomly shut off then on again was after the second time playing.  When I pressed in the "preset" button it shut off - flashed back on and showed the Spider 2.0 logo on the LCD.  At first I thought it was a fluke and shined it on.  But it happened again a while later.  Only this time it was while pulling my hand away from one of the FX knobs.  I thought "maybe a static discharge short?"  I tried to recreate the problem but nothing.  I played on it for maybe 20-30 min. at a time a few more days and it didn't occur. Then the next time while my brother was playing my guitar, I was messing with the "tones" or maybe the volume (as it likes to spike from not being adequately line leveled) and it shut off  and on again.  Then it happened again later and I was not touching it.  I have the amp plugged into a socket that shares a conditioner with a pair of powered monitors.  When ever I turn the monitors on and off they let out a little "pop"....I never heard them any of the times the amp would cycle.

Ok ....so there is the issue.  This seems to be an on going problem as there are a few post from people with the same problem.  This is the first amp I have purchased in 20 years.  This only after doing some extensive reasearch of "what is the best combo amp".... none of which mentioned this issue.....that was only discovered after first hand experience and joining this forum.

I bought the amp at Guitar Center....I'm going to contact them and see if I can trade it straight across for another one as its not 30 days old yet. I  just hope I don't end up with another one that does the same thing.  If they won't trade it for another 150w ....well...I'm not sure....?

Its like having a hot rod car that just stops running while your barreling down the freeway!!  Weak sauce.  Any help?

Thanks