Computer works in intervals
I'm using a home-built PC, which I've had since february this year. I've never had any problems with it, but now it's starting to behave curiously.
To and fro, when I start a program, open Mozilla and navigate in the start-menu for example, the OS completely freezes, and you can't do nothing except move around the mouse (clicking doesn't result in any visible action).
Then, after 30 seconds everything that I've tasked the computer to do happens, instantenously, including the things I clicked with the mouse when the computer was frozen.
This peculiar behaviour occurs mostly when I start several applications, though often resource-cheap.
I've never had this problem before, so I don't think it's due to my system specs, but rather I'm starting to suspect that the RAM is breaking down.
But it could as well be the bus, the HDD or the processor.
Anyone here who have encountered the same problem? What could possibly be the cause of all this?