DIMM modules not working together!

I have 2 modules from Crucial, both CL2 and both PC-133.
One is 128 meg and the other a 256 meg.
With the 128 in slot #1 and the 256 in #2, I immediately get registry errors and Explorer lockups.
The other way arround, I get random lockups and an occasional system reset.
Either module by itself seems to work fine.
Anyone have any idea as to what is causing this?
The OS is Win98 and drive is a WD 20 gig ATA100.
Thanks.

Depending on what MoBo you have there are a few BIOS settings you might try. Check the CAS# of the RAM you may have it set too high. If you have the option of changing the "DRAM Drive Strength" to Manual and try changinging the "Delay DRAM Read Latch Delay" to a slower speed ie 1.5ns.

I got the same setup as you have in my secondary computer (1-128mb + 1-256mb) except both are CAS3. Try changing your settings and see if that helps. I tried to put them at CAS2 and I got freezes, booting errors etc.
Abb