My initial problem.
I am trying to enable the media upload for the contributor role while in POST EDITING MODE.
The contributor role is unable to upload any media while EDTING A POST.
The Upload/Insert Tool (div "#wp-content-media-buttons") above the text editor is missing.
The "Media" option on the left admin menu disappears too as soon as we enter the post for editing. It reappears after exiting to any other admin page (e.g. Dashboard, All Posts, etc.).
However, the contributor role is able to upload media while creating a NEW POST or in the managing "Media" admin option page.
My contributor role has <Upload files> capabilities.
I realized that there was a conflict in plugins after disabling Role Scoper. Any ideas how may I resolve this problem?