Put a note on it and check the other two.

If that doesn't show anything, check each combination of two: AB, BC, and AC. If that doesn't show anything, check the other permutations of two: BA, CB, and CA.

If that doesn't show anything, you're bound to be back to something other than the RAM.

In fact, at this point I would guess that it is a power issue. While playing Flash video doesn't seem like it should be CPU-intensive, it is, probably as much as playing a game.