System hang and frequent boot failure

[sibeliusj]

Hi,

I use Linux Mint 13 in my system. Now the system is hanging very frequently. It is going to Kernel Panic too often. Few time i get the following error message while booting (attached image).

Config:
-------------
processor : AMD Sempron 2800+
Ram : 512 MB DDR1 RAM
Mobo : Asus K8V-VM motherboard

Note : I ran Memtest it showed no errors.

The processor temperature is around 47*C

Please help me at the earliest.