Exactly the same problem on my computer since I installed ubuntu 12.04.



System information report, generated by Sysinfo: 12/05/2012 02:04:34
http://sourceforge.net/projects/gsysinfo

SYSTEM INFORMATION
	Running Ubuntu Linux, the Ubuntu 12.04 (precise) release.
	GNOME: unknown (unknown)
	Kernel version: 3.3.5-030305-generic (#201205071254 SMP Mon May 7 16:56:02 UTC 2012)
	GCC: 4.6 (x86_64-linux-gnu)
	Xorg: 1.11.3 (20 April 2012  05:12:02AM) (20 April 2012  05:12:02AM)

CPU INFORMATION
	GenuineIntel, Intel(R) Core(TM) i7-2670QM CPU @ 2.20GHz
	Number of CPUs: 8
	CPU clock currently at 800.000 MHz with 6144 KB cache
	Numbering: family(6) model(42) stepping(7)
	Bogomips: 4390.17
	Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer xsave avx lahf_lm ida arat epb xsaveopt pln pts dts tpr_shadow vnmi flexpriority ept vpid

MEMORY INFORMATION
	Total memory: 7763 MB
	Total swap: 9998 MB

STORAGE INFORMATION
	SCSI device -  scsi0
		Vendor:  ATA      
		Model:  ST9750420AS      
	SCSI device -  scsi2
		Vendor:  HL-DT-ST 
		Model:  DVDRAM GT51N     

HARDWARE INFORMATION
MOTHERBOARD
	Host bridge
		Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
		Subsystem: ASUSTeK Computer Inc. Device 1147
	PCI bridge(s)
		Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b5) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b5) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b5) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 6 (rev b5) (prog-if 00 [Normal decode])
		Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b5) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b5) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b5) (prog-if 00 [Normal decode])
		Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 6 (rev b5) (prog-if 00 [Normal decode])
	ISA bridge
		Intel Corporation HM65 Express Chipset Family LPC Controller (rev 05)
		Subsystem: ASUSTeK Computer Inc. Device 1147

GRAPHIC CARD
	VGA controller
		NVIDIA Corporation Device 1058 (rev ff) (prog-if ff)
		Subsystem: ASUSTeK Computer Inc. Device 1652

SOUND CARD
	Multimedia controller
		Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 05)
		Subsystem: ASUSTeK Computer Inc. Device 1b43

NETWORK
	Network controller
		Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express) (rev 01)
		Subsystem: AzureWave AW-NB037H 802.11bgn Wireless Half-size Mini PCIe Card [AR9002WB-1NGCD]
	Ethernet controller
		Atheros Communications Inc. AR8151 v2.0 Gigabit Ethernet (rev c0)
		Subsystem: ASUSTeK Computer Inc. Device 1851