Strange, now I tried different combinations of options and nothing helps. Now
Triskel crashes every uneven login and every even login works. No matter what
option is enabled under desktop effects and even if they are disabled
completely.
However, when I turn the compositing on I can utilize all of the effects.
When I try enabling different effects for the window-closing event KWin still
crashes though, but I don't think it's abnormal, the effects must just be in
a conflict with each other.
It's only the uneven logins that crash KWin, even if "Enable desktop effects
at startup" is unchecked. It's strange how it is so consistant, every second
time you login everything works well.
I'll look into the ubuntu forums tomorrow, maybe it's an upstream bug?