problem: when startx or booting into lxde the panel was blinking all the time and i could not use/click it. i tried several things from copying settings from a to b or disabling profiles.
in the end it was a problem with the sound card settings which caused alsa to crash the volume button in the panel.
the error was that in sudo nano /etc/modules i had an entry snd-dummy for simulating a multichannel dummy soundcard. the solution was to uncomment (#) this line in /etc/modules