Music distortion & mouse lag

I bought a new pc and after i've had it on for a while, sometimes when i load a website and then move my mouse while it's loading the mouse kinda lags/jumps around to where i moved it. This also effects any music i have on at the time. The music distorts until it's done loading.

I've also noticed this a little when opening some programs (i've mainly been browsing the web so...). And sometimes out of the blue while playing online games.

What could be causing this?

What are the PC specs? That part was not filled out. But, it sounds like the new PC may not have enough memory?

(Taken from dxdiag)

Operating System - Windows 7 Home Premium 32-bit (6.1, Build 7600)
System Manufacturer - Gigabyte Technology Co., Ltd.
System Model - GA-MA785GMT-UD2H
BIOS: Award Modular BIOS v6.00PG
Processor: AMD Phenom(tm) II X4 955 Processor (4 CPUs), ~3.2GHz
Memory: 4096MB RAM

Graphic Card: NVIDIA GeForce GTS 250

Sound: Realtek High Definition Audio

In regards to memory i've not been doing anything my old pc couldn't do and i've only been using 50% memory and around 25% CPU.

Thanks for the specs. There is a separate section in the User CP where you post all of that.

As it's new, I would look at Interrupts (IRQ) as the sound usually is on a shared IRQ with a higher priority device. The mouse is a "high priority" device and should not be shared or shared with some lower priority device.

Also, get the latest BIOS and sound drivers, as they can be potential issues. Actually check for updated drivers for all the hardware as many times what comes with a new PC is not the "latest and greatest".