Win98 Frequently Accessing HD

For some reason my Windows 98se machine (with Norton Antivirus and a firewall running in the background) is frequently accessing my HD. If I open a program an let it sit for a bit the HD will stop accessing (and my system continues as normal). This is annoying when I am moving my mouse as the system seems to freeze whenever it is accessing the drive giving anything that I am doing very erratic movement.

Any suggestions?