Suddenly Hang / Freez in Any Window Manager

It seems that my computer doesn't match with Ubuntu (I guess) :( Why I said so,
because my Ubuntu often hangs without specific reason. These are the behaviour
of my computer when it hangs (freez):

1. The hardisk sometimes busy (busy red light indicator on) but sometimes not
2. It hangs right after I played an mp3 song on windows partition with JuK or
XMMS. -> this is the most often happens.
3. It hangs after I open aplications at the same time. Atau membuka aplikasi
secara bersamaan.
4. After it hangs, it becomes responsiveless (freeze as I said). I even can't
move to terminal (Ctrl+Alt+F1-4) nor gnome terminal can't respond to Ctrl+C

Sometimes I feel as if my screen just like wallpaper (to describe the freeze
without any indication like busy light). Is there any relation with noapic and
nolapic (even I've done that to my boot param)? Or kernel?

It happens in XFce4, Gnome and, if I'm not mistaken, KDE. I happens in Ubuntu
Hoary permanent (write to disk) and Ubuntu Breezy Live (sent package). This
freeze behaviour not happen in Knoppix 3.3 (about more than 1 year ago)

Please, could you fix this problem. I'm really desperated and afraid while I'm
writing my box suddenly hangs or when updating critical package.

Thanks

This the description of my computer. Sorry if it is too long.

Motherboard:
CPU Type Intel Pentium IIIE, 667 MHz (5 x 133)
Motherboard Name PCChips M756LMR
Motherboard Chipset SiS 630
System Memory 240 MB (SDRAM)
BIOS Type AMI (05/10/01)

Multimedia:
Audio Adapter C-Media CMI8738/C3DX Audio Device

Storage:
IDE Controller SiS PCI IDE Controller
Floppy Drive Floppy disk drive
Disk Drive ST380011A (80 GB, 7200 RPM, Ultra-ATA/100)
Disk Drive USB Mass Sorage USB Device (54 MB, USB)
Optical Drive LITE-ON CD-RW SOHR-5238S
Optical Drive SAMSUNG CD-ROM SC-152C (52x CD-ROM)
SMART Hard Disks Status OK

Network:
Network Adapter D-Link DFE-530TX PCI Fast Ethernet Adapter (rev.C)
Modem HSP56 MicroModem

[ BIOS ]

BIOS Properties:
Vendor American Megatrends Inc.
Version 062710
Release Date 07/15/97
Size 256 KB
Boot Devices Floppy Disk, Hard Disk, CD-ROM, ATAPI ZIP, LS-120
Capabilities Flash BIOS, Shadow BIOS, Selectable Boot, EDD
Supported Standards DMI, APM, ACPI, ESCD, PnP
Expansion Capabilities ISA, PCI, AGP, USB

[ System ]

System Properties:
Manufacturer PCCHIPS
Product M756LMRT
Version 123456890
Wake-Up Type Modem Ring

[ Motherboard ]

Motherboard Properties:
Manufacturer PCCHIPS
Product M756LMRT
Version 1.0

[ Chassis ]

Chassis Properties:
Manufacturer PCCHIPS
Version Version 1.00
Serial Number 123456890
Asset Tag 0123ABC
Chassis Type Desktop Case

[ Memory Controller ]
Memory Controller Properties:
Error Detection Method 32-bit ECC
Error Correction Single-bit
Supported Memory Interleave 1-Way
Current Memory Interleave 1-Way
Supported Memory Speeds 70ns, 60ns
Supported Memory Types SPM, FPM, EDO, Parity, ECC, SIMM
Supported Memory Voltages 3.3V
Maximum Memory Module Size 128 MB
Memory Slots 4

[ Processors / Pentium III ]

Processor Properties:
Manufacturer i
Version Pentium III
External Clock 133 MHz
Current Clock 667 MHz
Type Central Processor
Voltage 3.3 V, 2.9 V
Status Enabled
Upgrade Slot 1
Socket Designation Slot-1