My desktop works well at most time, but some times it flash.

[qasdfgtyuiop]

Hi,
I'm using Lenovo Ideapad Y460 laptop.  My computer performs well at
most time.  But sometimes my screen flashs about every 1 seconds.
Each flash will interrupt pull down menu and ibus IME input window.
The xev tool shows that each flash comes with the following events:

Expose event, serial 34, synthetic NO, window 0x2400001,
   (0,0), width 178, height 10, count 3

Expose event, serial 34, synthetic NO, window 0x2400001,
   (0,10), width 10, height 58, count 2

Expose event, serial 34, synthetic NO, window 0x2400001,
   (68,10), width 110, height 58, count 1

Expose event, serial 34, synthetic NO, window 0x2400001,
   (0,68), width 178, height 110, count 0

Expose event, serial 34, synthetic NO, window 0x2400001,
   (0,0), width 178, height 10, count 3

Expose event, serial 34, synthetic NO, window 0x2400001,
   (0,10), width 10, height 58, count 2

Expose event, serial 34, synthetic NO, window 0x2400001,
   (68,10), width 110, height 58, count 1

Expose event, serial 34, synthetic NO, window 0x2400001,
   (0,68), width 178, height 110, count 0

FocusOut event, serial 34, synthetic NO, window 0x2400001,
   mode NotifyGrab, detail NotifyAncestor

FocusOut event, serial 34, synthetic NO, window 0x2400001,
   mode NotifyUngrab, detail NotifyPointer

FocusIn event, serial 34, synthetic NO, window 0x2400001,
   mode NotifyUngrab, detail NotifyAncestor

KeymapNotify event, serial 34, synthetic NO, window 0x0,
   keys:  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0
          0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0

The results of some commands that may be useful:

$lspci
00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller (rev 18)
00:01.0 PCI bridge: Intel Corporation Core Processor PCI Express x16
Root Port (rev 18)
00:02.0 VGA compatible controller: Intel Corporation Core Processor
Integrated Graphics Controller (rev 18)
00:16.0 Communication controller: Intel Corporation 5 Series/3400
Series Chipset HECI Controller (rev 06)
00:1a.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset
USB2 Enhanced Host Controller (rev 06)
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset
High Definition Audio (rev 06)
00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI
Express Root Port 1 (rev 06)
00:1c.1 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI
Express Root Port 2 (rev 06)
00:1c.3 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI
Express Root Port 4 (rev 06)
00:1c.4 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI
Express Root Port 5 (rev 06)
00:1d.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset
USB2 Enhanced Host Controller (rev 06)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev a6)
00:1f.0 ISA bridge: Intel Corporation Mobile 5 Series Chipset LPC
Interface Controller (rev 06)
00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series
Chipset 4 port SATA AHCI Controller (rev 06)
00:1f.3 SMBus: Intel Corporation 5 Series/3400 Series Chipset SMBus
Controller (rev 06)
00:1f.6 Signal processing controller: Intel Corporation 5 Series/3400
Series Chipset Thermal Subsystem (rev 06)
01:00.0 VGA compatible controller: NVIDIA Corporation GF108 [GeForce
GT 425M] (rev ff)
01:00.1 Audio device: NVIDIA Corporation GF108 High Definition Audio
Controller (rev ff)
03:00.0 System peripheral: JMicron Technology Corp. SD/MMC Host
Controller (rev 20)
03:00.2 SD Host controller: JMicron Technology Corp. Standard SD Host
Controller (rev 20)
03:00.3 System peripheral: JMicron Technology Corp. MS Host Controller (rev 20)
03:00.4 System peripheral: JMicron Technology Corp. xD Host Controller (rev 20)
05:00.0 Network controller: Intel Corporation Centrino Wireless-N 1000
09:00.0 Ethernet controller: Broadcom Corporation NetLink BCM57780
Gigabit Ethernet PCIe (rev 01)
3f:00.0 Host bridge: Intel Corporation Core Processor QuickPath
Architecture Generic Non-core Registers (rev 05)
3f:00.1 Host bridge: Intel Corporation Core Processor QuickPath
Architecture System Address Decoder (rev 05)
3f:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 05)
3f:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 (rev 05)
3f:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 05)
3f:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 05)

$uname -a
Linux localhost 3.2.8-1-ARCH #1 SMP PREEMPT Mon Feb 27 21:51:46 CET
2012 x86_64 Intel(R) Core(TM) i5 CPU M 480 @ 2.67GHz GenuineIntel
GNU/Linux