My computer freezes randomly too, and after that I can't it start, if it was turned off. But if I have press "Reset" it goes on without problem.

I found in www that is kernel problem. 
There is my information if this can help to solve.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/507504

00:00.0 Host bridge [0600]: Intel Corporation 82845G/GL[Brookdale-G]/GE/PE DRAM Controller/Host-Hub Interface [8086:2560] (rev 03)
	Subsystem: Intel Corporation 82845G/GL[Brookdale-G]/GE/PE DRAM Controller/Host-Hub Interface [8086:2560]
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ >SERR- <PERR- INTx-
	Latency: 0
	Region 0: Memory at f8000000 (32-bit, prefetchable) [size=64M]
	Capabilities: <access denied>
	Kernel driver in use: agpgart-intel
	Kernel modules: intel-agp

00:02.0 VGA compatible controller [0300]: Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device [8086:2562] (rev 03)
	Subsystem: Intel Corporation Device [8086:5247]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 16
	Region 0: Memory at f0000000 (32-bit, prefetchable) [size=128M]
	Region 1: Memory at ffa80000 (32-bit, non-prefetchable) [size=512K]
	Capabilities: <access denied>
	Kernel driver in use: i915
	Kernel modules: i915

00:1d.0 USB Controller [0c03]: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 [8086:24c2] (rev 02)
	Subsystem: Intel Corporation Device [8086:5247]
	Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 16
	Region 4: I/O ports at e800 [size=32]
	Kernel driver in use: uhci_hcd

00:1d.1 USB Controller [0c03]: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 [8086:24c4] (rev 02)
	Subsystem: Intel Corporation Device [8086:5247]
	Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin B routed to IRQ 19
	Region 4: I/O ports at e880 [size=32]
	Kernel driver in use: uhci_hcd

00:1d.2 USB Controller [0c03]: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #3 [8086:24c7] (rev 02)
	Subsystem: Intel Corporation Device [8086:5247]
	Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin C routed to IRQ 18
	Region 4: I/O ports at ec00 [size=32]
	Kernel driver in use: uhci_hcd

00:1d.7 USB Controller [0c03]: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI Controller [8086:24cd] (rev 02) (prog-if 20)
	Subsystem: Intel Corporation Device [8086:5247]
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin D routed to IRQ 23
	Region 0: Memory at ffa7fc00 (32-bit, non-prefetchable) [size=1K]
	Capabilities: <access denied>
	Kernel driver in use: ehci_hcd

00:1e.0 PCI bridge [0604]: Intel Corporation 82801 PCI Bridge [8086:244e] (rev 82)
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR+ INTx-
	Latency: 0
	Bus: primary=00, secondary=01, subordinate=01, sec-latency=32
	I/O behind bridge: 0000d000-0000dfff
	Memory behind bridge: ff800000-ff8fffff
	Prefetchable memory behind bridge: e6a00000-e6afffff
	Secondary status: 66MHz- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- <SERR- <PERR-
	BridgeCtl: Parity- SERR+ NoISA+ VGA- MAbort- >Reset- FastB2B-
		PriDiscTmr- SecDiscTmr+ DiscTmrStat- DiscTmrSERREn-
	Kernel modules: shpchp

00:1f.0 ISA bridge [0601]: Intel Corporation 82801DB/DBL (ICH4/ICH4-L) LPC Interface Bridge [8086:24c0] (rev 02)
	Control: I/O+ Mem+ BusMaster+ SpecCycle+ MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Kernel modules: iTCO_wdt, intel-rng

00:1f.1 IDE interface [0101]: Intel Corporation 82801DB (ICH4) IDE Controller [8086:24cb] (rev 02) (prog-if 8a [Master SecP PriP])
	Subsystem: Intel Corporation Device [8086:5247]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 18
	Region 0: I/O ports at 01f0 [size=8]
	Region 1: I/O ports at 03f4 [size=1]
	Region 2: I/O ports at 0170 [size=8]
	Region 3: I/O ports at 0374 [size=1]
	Region 4: I/O ports at ffa0 [size=16]
	Region 5: Memory at 20000000 (32-bit, non-prefetchable) [size=1K]
	Kernel driver in use: ata_piix

00:1f.3 SMBus [0c05]: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) SMBus Controller [8086:24c3] (rev 02)
	Subsystem: Intel Corporation Device [8086:5247]
	Control: I/O+ Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Interrupt: pin B routed to IRQ 3
	Region 4: I/O ports at e000 [size=32]
	Kernel modules: i2c-i801

00:1f.5 Multimedia audio controller [0401]: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio Controller [8086:24c5] (rev 02)
	Subsystem: Intel Corporation Device [8086:0103]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin B routed to IRQ 17
	Region 0: I/O ports at e400 [size=256]
	Region 1: I/O ports at e080 [size=64]
	Region 2: Memory at ffa7f800 (32-bit, non-prefetchable) [size=512]
	Region 3: Memory at ffa7f400 (32-bit, non-prefetchable) [size=256]
	Capabilities: <access denied>
	Kernel driver in use: Intel ICH
	Kernel modules: snd-intel8x0

01:08.0 Ethernet controller [0200]: Intel Corporation 82801DB PRO/100 VE (LOM) Ethernet Controller [8086:1039] (rev 82)
	Subsystem: Intel Corporation Device [8086:3011]
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 32 (2000ns min, 14000ns max), Cache Line Size: 32 bytes
	Interrupt: pin A routed to IRQ 20
	Region 0: Memory at ff8ff000 (32-bit, non-prefetchable) [size=4K]
	Region 1: I/O ports at dc00 [size=64]
	Capabilities: <access denied>
	Kernel driver in use: e100
	Kernel modules: e100