Kad upalim iMac-a alu 20" mi desktop bez obzira na sliku u pozadini bude cijeli išaran u tonovima pozadine osim dock-a tj donjeg dijela i svih icona koje su vidljive. Nakon što s poiterom uokvirite cijeli ekran ta smetnja nestane i nema je više dok ne ugasite comp ili restartate ga pa se na trenutak pojavi ponovo kod gašenja i naravno kod paljenja.
Da dodam da se to uvjek ne dogodi ali je dovoljno često da me zabrinjava. Kontrolu hardwarea sam napravio i kaže da je ok.
Ima li tko kakvu ideju??

Try these suggestions:

Shut down your computer. Turn the computer back on and immediately hold down Command-Option-P-R, continuing to press until you hear the startup sound for the second time. This resets the computer’s parameter random-access memory (PRAM).

IMPORTANT: Resetting PRAM may change some system settings and preferences. Use System Preferences to restore your settings.

If resetting PRAM doesn’t solve the problem, reset non-volatile random access memory (NVRAM). When the “To continue booting ...” message appears, type “reset-nvram” and press Return. Then type “reset-all” and press Return.

If the computer restarts, you have successfully reset the NVRAM settings.

Smijem li pitati what if computer doesn't restart?

pa da nije uspio reset NVRAM-a ili je možda... ko zna..., probaj pa vidi...