Yeah .... This is a tough one.
One of the most expensive things we do around here is physical disk space to house all the content, images, files, backups, etc, etc. That said when the forum was originally set up we put limits on the amount of content users could upload. This was done merely for scaling purposes. Imagine 10,000 users all using 3MB of space and you can see quickly that we'd need to amass machines filled with nothing but physical disk space just to store member content. Now the problem has been outlined let's look at the solutions.
1. Put images in the gallery where there are no restrictions on file space, then link those images into your posts.
2. Remove some of the non-used or older upload content associated with your account by viewing this link. http://combatace.com/index.php?app=core&module=usercp&tab=core&area=attachments
3. Upgrade your account to a subscription account which will raise the limits on your storage space.
4. As your member status upgrades through the ranks (NEW, VALUED, JUNIOR, etc) so will your storage space. We did take into account that the members who have been here longer and have more posts need more storage space.
That's all I have for now. Hopefully one of those will work for you.
Thanks.
Erik