why my memory usage increses gradually by time

my computer memory usage increases gradually when i leave my computer open for a couple of hours without opening any program to use them see this pictures:

http://img193.imageshack.us/img193/1995/processesy.jpg

http://img10.imageshack.us/img10/633/totalh.jpg



u can see from the pictures that my pc is using now a total memory of 2.1gb

while in the processes screen i arranged the processes from larger usage to smaller so that u can see that nothing is using all of this memory

and memory usage continue on increasing until system hang and i have to make restart and after restart the memory usage return back to normal which is 800mb and then begins to increase again

i am using windows vista and 4gb of kingston ram

can anyone help me finding out what is the problem or what is using all of this ram

ps: it's not virus cause i scanned my pc with nod32 and found nothing

probably you installed some firefox add-on that pre-caches pages.
put here a screenie of your firefox extras, because it's that for sure.

http://img49.imageshack.us/img49/4779/80928666.jpg

http://img200.imageshack.us/img200/6788/73848182.jpg

there are some there that could be the cause, especially batch downloaders, accelerators, etc.
try tweaking around in their options, and see what's going on.

i think they are not the reason cause yesterday i didn't open firefox the whole day and the ram is still increasing is there any program to refresh the ram

there are several. i personally use on my servers MemTurbo 4. it does a great job.

Update Firefox. Maybe that version has a memory leak. Or use IE! like me. I really don't mind IE at all. Also you said that you didn't open Firefox yesterday and the memory dropped a lot? What program was suing the RAM? because firefox.exe should not always be running in the background as far as I know.

Some versions of firefox, I think the newest, cache or visit pages in your bookmarks for faster loading. I know that its caused issues with some people getting temp banned from some sites, because the bookmarked page is sending out many requests like a mini ddos attack lol.

classic case of memory leaking you gotta love it. its just one of those things that happen, it happens to me with firefox and I only have 3 addons installed. its sometimes due to programming errors in programs.

Any program that might have less than perfect code could cause memory leaks. Addons are mostly coded by more inexperienced people, which makes it even more likely to get leaks. Restarting your computer every once in a while will keep it nice and fast.