If the Beta doesn't work then you could also try a LW 4 version, as long as you're happy to use LW 4. Who knows where the incompatibility is - just maybe LW 4 won't have the same issue.

If you want to try LW 4 then check out this thread for links: Downgrading to LimeWire 4 from 5 & resuming incomplete downloads

If it's an issue with iTunes 9 then the LW developers will be notified & they can look into it.

Edit: Please let us know whether changing LW versions fixes the problem. Thanks.