hi,

in the last 5 months, my iMac (i5, 3.6 GHz, 4x2 GB RAM) four times died, beeping like Apple describes in
http://support.apple.com/kb/HT2538
(3 successive tones, a 5-second pause, 3 successive tones -- RAM does not pass data integrity check)

First time I thought corrupt video/cut data were causing the crahs, but not for crash no. 3 and 4.

I let Rember do 8 loops of checking all my memory, with a result that no errors could be found.
Apple Hardware Tests also say that my hardware is okay.

Can you give me a hint how to try to find out what's causing these crashes?

I removed all the RAM and put it back using different slots. Maybe one module was loose??? Don't know...