Actually, I have improved the "interruptability" of some archive operations, so the problems with big CAB files shouldn't occur much now. The only situation when the process may keep running for some time after the screesaver has been interrupted is when a big file is being processed - either unpacked from an archive (i.e. when the archived file is big; when only the archive (e.g. the CAB file) is big, it should be OK), or simply a big file is scanned (when "Test whole files" is set in the Screensaver task).
Eddy, what are your exact settings of the Screen-Saver task? What real screensaver are you using? (or, does it happen with any screensaver)?