Windows 98 Hanging Problem

We have Dell CPX H/J Latitude Laptops with Win98 SE (Office 97, Outlook 98, dialup, Winzip, Nortel VPN, etc.) and have a few systems hanging for up to 1 minute. Can be systems we just imaged (Norton Ghost) or systems in the field for 1-2 years. We have reimaged, and they work fine, but other cases require a replacement motherboard from Dell. Has anyone seen this or know anything about why Win98 just hangs, then recovers after a minute? Thanks. Steve Bouse/sbouse@answerthink.com