Howard, is this while using the icon in the post toolbox? If the icon is not working you could always hand type the [ img] [ /img] brackets in by hand, its a bit of a pain but I find if I copy the first [ img] bracket, then I can just paste the bracket on the end ot the addres and then add the backslash, yeah its a big head ache but its an option.
I havent had any trouble posting my pics using the icon, but then I have a system. I open my MLS webstorage click open the pics I want one at a time, copy the reference address and paste it to a Word transfer doc till I have all the ones I want, then I copy that block, and paste them into the post text box, then one at a time highlight each address, then copy and paste that address into the box that pops up with the image icon. Once I'm done I just hit submit, so far no problems.
Are you using something other that Microsoft? That could be most of the issue, but I'm not a computer guy so I cant help there.