| I recently purchased the 320+ v4.20 and a few times a day I get spikes on my logger software on my laptop. I have it hooked up via USB and generally get normal background radiation counts, but every once in a while I get counts up to 250 for a short period of time (1 to 2 minutes). I have never actually heard it happen or been able to see it happen, I only see it on my logger pro software. Any ideas? Could this be some kind of grounding issue? Another thing is that the device itself doesn't show that the max is 250, it usually shows about 30 to 35 as the maximum CPM.