agp lock up when graphics accelerated

when i push the hardware accelerater from none to the first click my sys freezes on the reboot .i have a savage 4 pro agp graphics card but it also locked up on my pci video card .I have a PII 300mhz ,98mb sdram,Dell trinitron mon Res 1024×768 16bit
60mhz what is the problem? also have dx6
any help would be appreciated. thanks Rob