Black screen problem on some android devices - Lags if games manage to start

I am developing a game and in 2 out of 12 android devices I tried it on there's a rendering problem: the game opens and the first scene is normally loaded. When newgame is pressed a new scene loads and on these 2 devices the screen goes black and nothing can be done. Nothing except one thing: if the android device goes into "daydream mode" with this black scene opened and then you exit dream mode, suddenly the game scene is normally displayed and the game goes on except for the fact that it lags a lot.

If can be of any help, the logs of these two devices say something like this when loading the new scene: D/Unity: fragment evaluation shader D/Unity: Compile failed. D/Unity: ERROR: 0:8: 'textureCubeLodEXT' : no matching overloaded function found D/Unity: ERROR: 0:8: 'return' : function return is not matching type D/Unity: ERROR: 2 compilation errors. No code generated.

The "faulty" devices are a nexus s and an acer liquid E2. I thought it was a GL ES 2.0 problem, but the game runs smoothly and with no problem on devices older than the acer, like a galaxy nexus and a galaxy s2.

Thanks in advance for any help!