Hallelujah!
By way of small miracle (and Google's penetration into the smallest nooks and crannies in the WWW) I managed to recover the 'forum with the blue background'.
Music-Web Forums
It's strange though how this one doesn't come up on searches with 'composer', 'composition', 'forum', etc. keywords. Fortunately I remembered a unique phrase in a particular post.
Anyway - I'm not affiliated with this forum. Just sharing the wealth!
