Well by the sounds of it it could be one of two things if your internet connection is working like normal.
1. Your memory has gone bad. In order to find out if this is true, use this cool little program: Memtest86.com - Memory Diagnostic Also, if your memory is bad, the companies who make the RAM often have lifetime guarantees, like Kingston.
2. This one is the more likely cause. There could be something that is causing your RAM to be taken up, possibly even a Virus or some form of Malware that is using up RAM while it does it thing, which is being an annoyance. To fix this problem use CTRL+ALT+Delete to bring up the task manager, then go to the Processes tab and look through it an try to find what is eating up your RAM. After you isolate what is causing it search for it using the windows search feature, then delete it, if you have trouble deleting it use a program called Unlocker and it will get rid of it nice and quickly.
If none of this helps, I would recommend Defragging your computer, something that too many people forget to do.