have a msi k7t266 pro 2 mainboard with 1600mhz athlon processor. running win98se have a 256mb ddr pc2100 (266mhz) memory chip, recently tried adding another 256mb 333mhz chip, which resulted in startup problems and windows failing to load, messages included ... problems with vtd, ntkern, initialising device ios, ndis, vcache, etc most times couldn't get as far as safe mode, even when could and used norton utillites to test memory , nortons reported memory problems, bios registers the ram and have tried changing sdram settings in the bios setup, with no luck, when using the 333mhz chip alone windows becomes unstable, back to using original pc2100 chip and it now registers 262mb in memory count at startup.... anybody any ideas? is this a compatibility problem between the different speed chips? msi have yet to reply and list no bios updates, or mention of any problems mixing chips , on their website.