Windows 7 Hangs Randomly

I've had my new computer since February and haven't had any major problems with it whatsoever.
However, theres one little annoying thing; randomly, the computer will hang/freeze.

I first noticed this when iTunes stopped playing music - it had frozen and I noticed the LED light on the desktop
was completely lit and wasn't flashing at all, as if it was doing something really big.
When it happens, normally I try and open Task Manager to see which program is using up the most Memory
but Task Manager only opens when the computer has unfrozen and music has started playing again.
I can continue browsing on whatever Internet page I am on also, so the whole computer hasn't frozen but sometimes
when I try and see if I can open other programs via the Taskbar, the timer appears next to the mouse.

These hangs happen completely randomly; its only ever done it once during a day but sometimes it can go quite a few days
before it does it again and the hangs only last for a few seconds, once or twice though it has lasted for a few minutes.

The common thing is normally it happens when i'm playing music via iTunes and I only notice its frozen because music
has stopped playing and iTunes becomes unresponsive, so i'm thinking it could be iTunes causing the lag as it can freeze
quite a bit normally anyway (I have made sure though i got the 64-bit version).
I think once it happened when I wasn't playing any music, but iTunes was still open.
Its not a virus/malware/etc... and I've checked the Event Viewer directly after a freeze to see if any error was reported
when the issue occured but nothing.

Its not a huge issue as normally it only lasts a few seconds but its always slightly annoyed me.
Any insight would be appriciated.

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Running Windows 7 64-bit, 4GB RAM, AMD Athlon II X3 435 Processor, 2.90 GHz