Will try the latter (Android_808, could you do the same, for consistent results? Also I may be of non-consistent and non-real time availability for some time), as for the former, sadly, it happens to be completely random.

Well, maybe not *completely* - for me, it seems to appear most of the time, when I'm doing things that require "Scroll by drag" (like browser). But nothing more specific than that. It appeared on wide range of programs, from browser, to lonewolf4maemo, so I have no idea how to narrow it.

/Estel

// Edit

another thing that comes to my mind - bug is always related to screen becoming blurry for a second, like the topmost window become considered a background one. then, it returns to normal, but no input is detected, unless I do mentioned slide-lock & power-key-to-lockscreen & unlock combo.