Mixing Pc100 64mb and Pc100 128mb

Hi everyone, my PC has 2 ram slots and have to sticks of pc100 64mb
(generic)(total 128mb), well i decided to buy a used stick of pc100
128mb(kingston) to upgrade to 192mb or ram, what i did is, take out one of
the 64mb and replace it with the 128mb, after installing it booted fine, it
read that my pc has 192mb of ram, however after 2 days the icons in my
desktop looked all blurry even sometimes after boot up, the icons wouldn't
appear just the names appeard, so it was obvious it had something to do with
the ram i installed.

What i did is take out the 64mb stick , and now i just have the one stick of
128mb (kingston) and the icons seem fine no problems so far (installed like
10 min ago from positing this). My guess is that because the ram sticks are
from diffrent manufacturers they are bumping heads and the fact that mixing
speeds is not a good idea , so i guess ill be looking for another pc100
128mb of ram, do you all think its ok if its another brand and not kingston
(what i have now) or even a generic brand (there a lot cheaper lol). Tia

Ps, I do have another stick of pc133 128mb of ram, but thats sort of a lost
cause, i tried to make it work by puting it in my pc by itself , everyway
you can think of, and it did not even boot, just showed a black screen.