According to a November 2007 list I found online, however, Worms Forts: Under Siege is supposed to be completely backwards-compatible (unlike, for instance, the XBox version of Grand Theft Auto: Vice City, which is subject to severe clipping issues on the 360). So, all I can suggest is maybe running the disk through some sort of cleaning system, like a DiscDoctor or something along those lines, to rid the surface of contaminants and repair any minor scratches that might be interfering with the disk read (since the system uses DVD-ROMs rather than CD-ROMs, the reading capabilites of the laser aren't so robust), and then try it again.
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Sodium is a metal that reacts explosively when exposed to water. Chlorine is a gas that'll kill you dead in moments. Together they make my fries taste good.