at some times......when i play game and exit it......the process for the game stucks in task manager.i cant end the process by any ways.this also happens with an other program...such as windows media player,etc.when the process is stuck.....i cant shut down my computer.....the blue screen saying "windows is shutting down" appeared but my computer wont shut down no matter how long i wait...am i infected?

Are you finding any suspicious processes in Task Manager? When you experience or encounter strange behavior, always check for new, unknown or suspicious processes that may be running on your system.

Shutdown problems can be symptomatic of a variety of things to include hardware/software issues, mismatched RAM, other programs hanging or unresponsive in the background, unsigned device drives and even malware. Another reason for slow shutdown is too many services running.

To get hung processes to end automatically when you shutdown, see Automatically Close Applications Not Responding at Shutdown: AutoEndTasks registry tweak. This step involves making changes in the registry. Always back up your registry before making any changes. If you are not familiar with working in the registry, then you should NOT attempt to make any changes on your own.

Another thing to try is downloading and installing the User Profile Hive Cleanup Service which helps to ensure user sessions are completely terminated when a user logs off. System processes and applications occasionally maintain connections to registry keys in the user profile after a user logs off. In those cases the user session is prevented from completely ending.

Also see:
XP Shutdown and Restart Troubleshooting
Troubleshooting Windows Shutdown Problems
Windows stops responding during Windows XP shut down
Troubleshoot shutdown problems in Windows XP

i already did the registry tweak but now im not sure whether it still stucks or not....
also....i think my system is not clean(have malware/spyware).because i installed kaspersky anti virus 2009 and when i scan i get some trojans....i cant complete the scan because the scan always stuck at 2%.....but it ask me to restart my pc to completely remove the trojan.so i restarted my pc.after that i scan again i get the same trojan....
now may be my system is infected....
sorry for not telling this earlier i was in rush when i opened this topic....

Try running your scans in "Safe Mode".

You can also do this:

Please download and scan with Dr.Web CureIt. Follow the instructions here for performing a scan in "Safe Mode".
-- Post the log in your next reply and let me know how your computer is running.

here is the log but i stopped the scan while it is scanning...it is not a complete log because i have emergency during the scan so i have to stop it...i will redo a complete scan
maybe tomorrow and post the full logs.by the way...before i do this scan i have process stuck problem again.... I'm already done with the registry tweak but it still happening...
heres the log...
hmr62.sys;c:\windows;BackDoor.Bulknet.112;Deleted.;
Desktop_.ini;C:\Documents and Settings\ivan\Desktop\Tioman\tioman1;Win32.HLLW.Gavir.ini;Deleted.;

I understand. Emergencies happen and real life issues come first.

Please note that hmr62.sys was related to a rootkit component. Rootkits are very dangerous because they use advanced techniques (backdoors) as a means of accessing a computer system that bypasses security mechanisms and steal sensitive information which they send back to the hacker. Many rootkits can hook into the Windows 32-bit kernel, and patch several APIs to hide new registry keys and files they install. Remote attackers use backdoor Trojans and rootkits as part of an exploit to gain unauthorized access to a computer and take control of it without your knowledge.

If your computer was used for online banking, has credit card information or other sensitive data on it, all passwords should be changed immediately to include those used for banking, email, eBay, paypal and online forums. You should consider them to be compromised. They should be changed by using a different computer and not the infected one. If not, an attacker may get the new passwords and transaction information. Banking and credit card institutions should be notified of the possible security breach. Because your computer was compromised please read How Do I Handle Possible Identify Theft, Internet Fraud and CC Fraud?

Although the rootkit was identified and removed, your PC has likely been compromised and there is no way to be sure the computer can ever be trusted again. It is dangerous and incorrect to assume that because the rootkit has been removed the computer is now secure. Many experts in the security community believe that once infected with this type of malware, the best course of action is to wipe the drive clean, reformat and reinstall the OS. Please read "When should I re-format? How should I reinstall?" and "Help: I Got Hacked. Now What Do I Do?".

how do it reformat or reinstall the os?

Please review "How to partition and format a hard disk in Windows XP".

These links include step by step instructions:
"Clean Install Windows XP".
"Reformat & Clean Install Windows".
"XP Clean Install Interactive Setup".

Reformatting a hard disk deletes all data. If you decide to reformat, you should back up all your important documents, data files and photos. The safest practice is not to backup any .exe files because they may be infected. Some malware may disguise itself by adding and hiding its extension to the existing extension of other files so be sure you take a close look at the full name. After reformatting, as a precaution, make sure you scan these files with your anti-virus prior to copying them back to your hard drive. Don't forget you will have to go to Microsoft Update and apply all Windows security patches.

Also see "How to keep your Windows XP activation after clean install".

If you need additional assistance with reformatting, you can start a new topic in the Windows XP Home and Professional forum.