I have recently bought a new 128MB RAM chip from Crucial (as 100 percent guarenteed to work with my system by their online scanner) which although shown as installed on the pre windows bootup screen then proceeds to crash Windows with the following message: HIMEM.SYS has detected unreliable XMS memory at address 04002000 then XMS driver not installed HIMEM.SYS is missing. I have tried swapping the orignal RAM chip with the new one but then the entire system freezes at bootup and I have to manually turn the PC off at the mains. I have also tried all variations of slots with both chips none of which work except the orignal 64 meg chip which does work in any slot so it cannot be the slots. I have also searched various websites and tried the most commonly recommended advice of turning the external memory checker off which doesn't correct the problem either. Any help would be greatly appreciated as I am at my wits end.

Sounds like their scanner is wrong and that you have not purchased RAM of the right type for your machine. Derek.W

Copy down the numbers off the old stick. Somebody here can read the numbers, maybe ya got the wrong speed chip. If the old one says PC66 and the new one says PC33 ... Best

For a P-III at 450 mhz, the ram stick should be PC100. PC133 should work but I've seen some that specify 'to be used only in 133 mhz systems'. You may want to post back info on the motherboard or computer manufacturer.

Are you sure you bought SDRAM and not DDRAM? That would definately account for your errors.