Video card -- persistent image behind window when switching to a diff desktop/window

[ubuntu at r322.com]

 Hi:

 Here are 2 pictures of the problem:

 https://picasaweb.google.com/116056519207953736352/Ubuntu?authkey=Gv1sRgCJqIoaaD6fGJZQ#5598400581668082738

 The first one is a term window and gimp in the background (virtual 
 desktop 2.)

 The second is me switching to desktop 1 and the gimp application that 
 was at the bottom of window 2 remains on window 1.

 If I drag the browser window around on window 1 it will go over the 
 persistent gimp image and remain there all choppy until it's replaced 
 with another image.

 Any ideas? This is a HP ProBook 6450b.


 rob at rob-HP-ProBook-6450b:~$ lspci | grep VGA
 00:02.0 VGA compatible controller: Intel Corporation Core Processor 
 Integrated Graphics Controller (rev 02)
 rob at rob-HP-ProBook-6450b:~$ sudo lshw -C video
 [sudo] password for rob:
 PCI (sysfs)
   *-display
        description: VGA compatible controller
        product: Core Processor Integrated Graphics Controller
        vendor: Intel Corporation
        physical id: 2
        bus info: pci at 0000:00:02.0
        version: 02
        width: 64 bits
        clock: 33MHz
        capabilities: msi pm vga_controller bus_master cap_list rom
        configuration: driver=i915 latency=0
        resources: irq:46 memory:d0000000-d03fffff 
 memory:c0000000-cfffffff ioport:4050(size=8)

 rob at rob-HP-ProBook-6450b:~$ cat /proc/cpuinfo |grep -P 
 "processor|vendor_id|model name"
 processor	: 0
 vendor_id	: GenuineIntel
 model name	: Intel(R) Core(TM) i5 CPU       M 460  @ 2.53GHz
 processor	: 1
 vendor_id	: GenuineIntel
 model name	: Intel(R) Core(TM) i5 CPU       M 460  @ 2.53GHz
 processor	: 2
 vendor_id	: GenuineIntel
 model name	: Intel(R) Core(TM) i5 CPU       M 460  @ 2.53GHz
 processor	: 3
 vendor_id	: GenuineIntel
 model name	: Intel(R) Core(TM) i5 CPU       M 460  @ 2.53GHz
 rob at rob-HP-ProBook-6450b:~$ uptime
  09:42:09 up  1:03,  5 users,  load average: 1.14, 1.18, 1.21
 rob at rob-HP-ProBook-6450b:~$ free -m
              total       used       free     shared    buffers     
 cached
 Mem:          3755       3398        356          0        192       
 1589
 -/+ buffers/cache:       1615       2139
 Swap:         3814          0       3814