I clicked icons in windows XP, no programs was opened. Or it took long
time to be opened. But there were no error messages in the screen. But
I can open application programs at the program files list of the Start
section. So I checked Virus with Norton, There were no Viruses. How
can I solve this probelm?

Try running adaware software
I like spybot S&D
You could also try Adware.
This will probobly solve your problem

You can get both for free of download.com

It seems as if this question requires a bit more detail:

What are the specs of your system; ex: Processor, Ram, Hard Drive
space.  Is it Windows Xp or Windows Xp Professional.

If you hit Alt+Ctrl+Del  then click on processes - is there an
exremely high amount of CPU usage on any specific program?

One program may be using an extremely high amount of CPU and Ram. 
This could cause your computer to "hang." If that is the case, you may
have to "end task" on that application in order to maintain proper
computer usage.

I hope this helps.  If it does not work or I am completely off, please
try shutting down the computer and then turning it back on.

-Ken

Sounds to me like there is a problem with Desktop.ini
Do the following:
1) Log in as Administrator
2) Open My Computer, Select Tools\Folder Options\View. Select View All
Files.  Unselect Hide Protected Files
3) Go to C:\Documents and Settings\username, where "username" is the
name you log in with. Double-click this folder
4) Inside the folder, you'll see a list of other files and olders. 
Locate Desktop, and open it up.
5) Locate the file called Desktop.ini.  Right-click the file and select Rename.
6) Locate and hit the button labled "End" on the keyboard.  Now hit
Backspace 3 times.  You've just deleted the 'ini' extension.  Type OLD
and hit enter. The file should now read "Desktop.OLD"
7) Close all folders, restart the computer, and log on as yourself.

Delete Windows!

Winlogon.exe is often the problem. This is however a system program
and does become corrupted by viruses or Trogens or some unknown event.
MS knows about this problem but they don't know how to fix it and are
therefore ignoring it. They will make us buy an upgrade in a year with
new bugs.