i cannot see any adsense advertisement int any site

your system IP may be blocked from showing ads by google or from site,you better email this to google as soon as possible to avoid future problems.

 

i found the cause of problem at last.
it is host file of my computer located in Windows\System32\Drivers\etc\
open this file with an text editor and remove ads.googlesyndication.com line

thanks very much..

 

Oh my!
Glad you knew what was wrong. I will apply this solution to my friend's PC.
How did you get to know that?

 

I know it's been solved, but to anybody else with a similar problem:
friend of mine is using zonealarm to disable all JS, make sure that your JS is loading, also do a view source on your page and make sure that the google ad is actually there.

 

I downloaded a program called "Security Task Manager". When i ran it, it alerted me telling site1.com, site2.com... is added to my host file and if i want to edit this file. i clicked yes and i found there ads.googlesyndication.com
i remove this line, that's all.