No, it's not the driver, it's well connected. I guess it maybe the protection on the batteries, although I can't say that for sure since I can't read the japense on the label. But it has been more stable recently.
Got the batteries and fired it up today.
The batteries work okay, but they behave a little weird... When I fire up the laser for the first time, it starts out not so bright, on the second time it's way brighter, then it goes down a little on the third light up, and finally it start going...
Well I bought 10 of them on DX (panasonic batteries) that are, according to the reviews, really realiable. I'm gonna give those a try. If they empty out too fast, I'll go with the one you're recommending.