I suspect you are refering to the default IDE. I just tried the download link and get the same error.
There are 2 things you can do:
1. Email thegamecreators and tell them that the link is down explaining that it is BOTH of the links on the following page: http://darkbasicpro.thegamecreators.com/?f=ide
You can contact them by going to the following page: http://darkbasicpro.thegamecreators.com/?m=contact_support
or
2. Change IDE. There are some good ones out there. Search for Twilight, BlueIDE, JaPROe, or darkriders editor (not sure what its called) on the program annoucements and work in progress forums.