Do you know Task manager?Yes of course !!All Computer have Task manager inside him,but this Default Task Manager have so much weaknesses.(after I know about this weaknesses,I have no doubt why many virus are loving Windows !!)

The 1st weaknesses is : Task manager Does not tell where the processes's .exe files are executed.(ex:for svchost it must be C:\WINDOWS\system32\svchost.exe).Then if it's not inside C:\WINDOWS\system32 means it is virus !!

The 2nd weaknesses is:It's could be easily Disabled from Registry !!(So if the viruses afraid his .exe could be ended from task manager,then it will just disabled the task manager).

The 3rd and THE WORST is :It could not Kill more than 1 process in one time !!(Nowadays,A virus will be separated into more than 1 .exe within different directory,so if the user Kill the 1st .exe,the 2nd exe will reproduce the 1st exe,and if the user kill the 2nd .exe,the 1st .exe will reproduce it !!)

Here is the resolve :

For the 1st weak point : Use another task manager,like processExplorer,this one is recommended by microsoft,Process Explorer not give the directory of the .exe files,but in addition it gives the .exe files description(ex:WindowsExplorer).Here's the Page about ProcessExplorer.

For the 2nd weak point : Use ProcessExplorer like above(but sometimes the viruses could use all of your bandwidth or disable your internet connection,so this way's ineffective), OR change the Administrative Templates via Gpedit.msc or Registry editor(Go through Run,type gpedit.msc/regedit and proceed).But this way(through gpedit.msc/regedit) is ineffective too,why?Because the viruses can disable both of them too...There's an Easier way for this !!
Open your Notepad,and type :

@echo off
Tasklist
Pause

And then save the file with name Tasklist.bat(Don't forget to write the ".bat",because if it's not written then the notepad will automatically save the file as .txt).Then Open the File !!
Note:Tasklist is different with Task manager,so wether if the task manager nor registry is disabled by the virus,Tasklist will still working.

The 3rd weak point :How to kill more than 1 process at one time !!(To prevent the viruses from reproducing itself)
There's another Default Task program inside windows,called Taskkill.
Open Notepad again,then type :

taskkill /F /IM *whatyouwanttokill*.exe

Save it with "yourbatfilename".bat (you can change "yourbatfilename" to anything,but don't change the .bat file ekstension).
Example: If I want to kill Task Manager,just type

taskkill /F /IM taskmgr.exe

Then What if you want to kill 5 Processes in one time ?Just type:

taskkill /F /IM example1.exe
taskkill /F /IM example2.exe
taskkill /F /IM example3.exe
taskkill /F /IM example4.exe
taskkill /F /IM example5.exe

Don't forget to change the example1 - example5 to the file names that you want to kill.