Yeah, newest firmware installed.
I powered it on for 6 times yesterday - First time, only for 10 minutes (during lunchbreak), tried via headphones - worked.
Than in the evening: Second time. Via headphones again, everything cool, than i let it on (unplugged the guitar), but got me something to eat. When i went back to play again, the headphones at first worked normally, than i did all the USB-driver installation and connected the Axe to the computer (everything strictly according to manual), than played again, but stereosound went to mono, back to stereo, than sounded "broken", than it was "half-right" (like a monotrack in a 60/40 setting), than no sound at all.
Restarted the unit, connected active studiomonitors -> no sound. rechecked connections, they were correct, but no sound.
Restarted the unit. Works. sound is there. Sound is good.
So, is tarted noodling around, browsing through presets to get a first impression, and than finally thought "Its time to start builing my sound.." - so i took the empty patch, added an amp, added a cab, did a few adjustements in the amp-settings (gain/bass/mid/treb), than went to the cab, and tried different mics...after the 5th mic, no sound anymore, the unit froze, and the front-LEDs went into some kind of "test-mode", cycling through in a regular pattern, each single LED beeing on for about half a second or so, than the next, and so on...
waited and watched, but it started over again, so i turned the unit off, waited a few minutes, powered on - everything fine again. But at this time I already was a bit pissed to be honest, so i turned it off, went to bed.
Just recheck today morning, worked.
So it IS wokring right now, but to be honest - when out of 6 times, 3 times it wont work (correct), its not a unit i want to rely on in a live setting. I sent an email to G66, will wait what they say.