well, for one...different kinds of ram arent always going to work well together, despite having similar specs...this may be what is causing them to be unstable. are you having any problems with booting up where the system is saying amount of system memory has changed? i had to take ram out ofa computer because it kept crashing or having troubles booting up...the decrease did make a dent in performance, but at least the computer was stable and more reliable.
on another note.....are you going to spell "channel" right any time soon...?