Which programs are running? Might be able to pin point it... other wise, we would have to guess.

 

get the app from market called.. spare parts.
it will tell you which program is running all the time, if there is an issue.

but i really dont think you need to do that.. android does a lot of things different from WM and other OS. things running in the background is what it does best. so that you can have things faster. it will kill things if it needs to ..to give u more memory.

do a little search on task killers and you will find a lot of discussion on why you need to leave it alone and not use task killers.

also do a little search on internal memory killers. there is an internal process that you can edit so android kills more background process earlier, so that you can have more free memory.

all in all... android and free memory is a miss-understanding to the older way of thinking. There is a reason that android did not give you an easy way to turn off apps. Android is designed to take care of it for you... you only have to use the phone and the rest is taken care of for you.

that being said... there are programs that are not designed perfect and might have memory leads and not move to the background correctly. So, then if you find them, uninstall and dont load it again, unless the dev has corrected it.