After setting up a new iMac G5 recently there were a plethora of software updates to be downloaded. The problem is that after the first time where the update window showed two pages of available updates it subsequently refused to show any at all.
Thinking that the problem might have to do withDirecWay as the DirecWay XML-RPC does.
However, the fault seems to be with OS X instead. If there is a cache file in the following directory remove it and all should be well:
/Users/yourname/Library/Caches/com.apple.softwareupdate/00/14