I've only got the 2003 version, but there should be an option to configure Norton SystemWorks. There should be a startup tab. Tick off CleanSweep items and tick off Norton Utilities items (especially SystemDoctor), unless there are specific things you want to run at startup. Leave Norton AV auto-protect ticked. The 2004 version may have added functionalities, so I can't comment on those.
If you use XP, click Start, Run, type services.msc and press Enter.
See if there is an entry called Speed Disk service. Double click it, and for the startup type box, click the drop down list and select Manual. OK. Don't change anything else in Services unless you know what you're doing.
Restart. See if it makes any difference.