The problem may be related to the setting of the Front Side Bus, which may be set to a different speed to your CPU. Changing the bus speed may solve the problem.
The old Duron had a clock speed of 200Mhz (100Mhz bus). You almost certainly have one of the newer Applebred 1.6 units (model number - DHD1600DLVC1) which are 266Mhz (133Mhz bus).
Make sure jumper 4 (JP 4) is set on pins 2 & 3 for 133/266Mhz.