http://www.dds6qkxpwdeubwucdiaord2xgbbeyds25rbsgr73tbfpqpt4a6vjwsyd.onion/w/index.php?title=Dev/VirtualBox&curid=6793&oldid=83656
The issues of the Open Watcom License are explained in this thread on the Debian Mailinglist. In summary, there are issues surrounding the contradictory language of the license, the assertion of patents against software that rely upon it, and the placing of certain restrictions on software uses.