Win7 system, current Norton Internet Security and Anti-Virus. Both Internet Explorer and Mozilla Firefox, shortly after restart or coming out of sleep, will suddenly begin intense disk activity, so intense that the cursor freezes. CTRL+
ALT+DELETE has no effect while the disk activity is occurring. When on a wired Internet connection, can disconnect Ethernet cable and disk activity continues. Even with Task Manager already running, cannot click and view Task Manager because cursor is frozen. After disk activity concludes, everything is "normal". Full disk scan reveals nothing except some tracking cookies. What could be causing this extremely annoying problem?