Odd blu ray problem?

Hi, hope you could shed some light.

I recently got a ps3 off ebay,reflowed it and solved ylod. Runs like a dream, nice and quiet, lovely warm air out the back etc, but a problem with the blu ray as follows.

I would not read games, but played cd and dvd fine. So i went into recovery mode and restored file system, then went back into recovery and rebuilt database. Presto,, all working perfect. I then did some tecnical change to my system, cant remeber what, but lost blu ray playback again. I repeated the recovery process and it works.

Last night i was stopping at my dad, he has hd telly , so connected with hdmi, and i got no BR playback, but doing the recovery menu for a third time solved the problem.

It seems if the system is left alone it works perfect, but any change and i lose BR playback, would anyone have any ideas?

regards Shaky