Problems with selecting verticles(wrong ones selected)

I have problem with selecting verticles
when i want to choose a group of verticle and when i choose the verticles,they wont be the only verticle selected.
have i pressed/unpressed anything

some pics

Before selecting
http://img75.imageshack.us/img75/5360/problem11ev.png
after selecting
http://img75.imageshack.us/img75/7586/problem29ta.png

I noticed that verticles are selected correctly in wireframe mode

do you have antialiasing enabled in your driver settings? if so, turn it off or set it to “application preference”

It almost looks like it’s selecting edgeloops (you have some bad geometry if I see the image correctly). Maybe you have ALT key pressed or stuck on your keyboard (mine gets stuck sometimes - even though the key is up).

some better pics

before selecting
http://img355.imageshack.us/img355/701/problem30xe.th.png

after
http://img483.imageshack.us/img483/5433/problem49sp.th.png

What’s your graphics card model and RAM?

graphics cart
ATI RADEON 9600
256MB DDR
CRT,DVI & TV-OUT
8X AGP
(I installed this graphics card yesterday,so may it be the cause?)

RAM

512+256MB

I’ve noticed the same problem on the ATi card and I have a solution:

it seems that vertices select only works in wireframe mode or solid mode with occlusion turned OFF. Otherwise blender selects the wrong vertices.

I noticet that too
Also,pressing the"limit the selection to vilible button "will let me choose the right verticles

turn off antialiasing [or set it to “application prefrence”] in the display properties [hit the advanced button on the settings tab… or go to the “catalyst control center” if you have that installed]