iMac not starting

Hi everyone,

I have an iMac9,1 Intel Core 2 Duo (late 2009), and some days ago, while I was turning it off, realized I had a DVD inside that I wanted to remove, so I pressed the eject button and it ejected the DVD just one second before it turned off.

The next time I turned the iMac on, I could hear the hard drive starting, but nothing further than that - no image/light on the screen, and no startup sound.

I then tried to restart it resetting the PRAM (pressing Command, Option, P, and R at startup), and it worked, but the iMac keeps doing this from time to time.

I already ran the Hardware Apple Test (pressing D key at startup), and no problems were found (I did the extended test which took more than one hour).

The last time I turned my iMac on, it did the same thing, but this time, I head three loud BEEPs.

Could it be a RAM memory problem, although the Hardware Test didn’t find any?

Could it be because of ejecting the DVD improperly?...

Thank you all sincerely!