Unable to insert pictures using the browse function

No one is able to add a picture using the browse funtion in the main forum,  We can add pictures to the gallery from our pc's but not into the forum.  Does anyone have any idea why this is and how we can fix it?
The error message we get is The upload folder is full. Please try a smaller file and/or contact an administrator.  The setting is at the highest possible according to our administrator!!

Check if you have space for attachments under Admin -> Attachments and Avatars - File Maintenance

Yeah each forum is limited on the total amount of space everyone has for uploading. You can host pictures somewhere else like photobucket or tinypic and then use a bbcode to display it in a topic.