Your problems are being caused by apps your running so you need to do some cleaning up of running processes.
I would first empty your temp folder C:WINDOWS\Temp, then your Temporary Internet Files same directory & all your cookies. You can do theselast two through Internet Options or their respective folders.
Now run Scandisk & Defrag, if you run into any problems where either won't finish, you'll need to disable any running programs ie; screensavers, antivirus, memory managers, Norton Systemworks, apps set to check for updates like Realplayer, Mediaplayer any scheduled tasks.
Once you've run scandisk & defrag, I'd suggest using a registry cleaner, Norton's does a ok job but would suggest you also download RegCleaner from this sitehttp://www.vtoy.fi/jv16/index.shtml
I use both but mostly RegCleaner partly because it also has extra features such as a page which lists all your startup apps & allows you to delete them from startup better than Windows. The registry cleaner is also more user freindly than Norton's. I'm also assuming your running WinME not XP
You should also download Ad-aware & run it, you can get it at most download sites or do a Google search. Post a comment or email me if you need more help.