It's a problem with the entire forums and something that technically should be taken up with the forum admin as the Monkey Island Discussion forum
is a sub forum of LucasForums
. To get in touch, go to the lucasforums site and find the Feedback forums (the big one, not this one) and ask them there.
Actually don't because, some has recently taken this up with them and asked the exact same question.
Unfortunately I doubt they have any plans to rectify it because
a) you can fix it yourself by doing what Thrik said above and
b) it's not that big a deal and the forum admin have better things to be doing with their time, like actually maintaining the forums and making sure Mojo doesn't go down.