Missing Memory

I didn't know what section to put this in but this sounded the most reasonable. The other night I had 3.9 GB of memory (Yeah I know its not a lot, lol) and when I checked my computer and the C: drive icon a few hours later, it said 3.4 GB. I ran CCleaner, and ATFCleaner and nothing changed. The next night it came down to 2.9GB, I ran the same programs and still nothing changed. I haven't downloaded anything and only visited a few internet pages. I don't understand why this is happening. Please enlighten.

 

do you have an integrated graphics chip?

I have 512 RAM in my cheap system...and integrated nVidia 6100..and was only showing the RAM at 384...found out integrated graphics share the RAM...so yea.