Looks to be because you have linked them from a google mail attachment, obviously this isn't working...

I have found the best way to attach photos is to do it from photobucket or something similar.
It means a bit extra work for you but the links work properly every time, plus the forum doesn't have the problem of having all those megabites.

Go here, http://photobucket.com/ and sign up for an account, 'tis completely free and you can call yourself anything you like.

Here's a link to mine for example. http://s1036.photobucket.com/user/Buggabear/library/Destination%20Unknown?sort=3&page=1

As you can see you can have different albums for what interests you, it's also good to let others see what you are up to, you can make it private as well and just share with friends/family if you prefer.

Once you have uploaded your pics (upload button along the top bar) you can then past a link in here very easily.
Just hover your mouse over the picture you want and you will see a little gear thingy show up in the top corner, again hover your mouse over this (don't click anything yet) and a drop down box will appear, chose (left click) 'get links' and another box will appear, like this...


Go to the bottom option 'IMG codes' and left click on it.
That code is now copied and ready to past in the forum.
So now all you do is right click in your post where you want the picture to go and click 'paste' and your done.
Like this.


Once you have done it a few times it is pretty easy, and as I mentioned you will have pictures up you can direct others to go and visit when they want.

Hope this helps,
Cheers,