How did you try to delete it?

Did you try Malwarebytes:?

http://malwarebytes.org/

Because it is one of the best free virus removers.

i'm using kaspersky virus it didn't detect and i used spy sweeper to remove it but it also didn't detect the virus. then i found the file in system32 and used shift+del but it didn't worked. it gives a warning the file is open in another process.

Check running processes, and find kill the process. Then try deleting it. If you can not delete it after killing the process, then boot in safe mode and try deleting it. Safe mode should not allow the virus to load into memory. If this doesn't work, malwarebytes as recommended above should be able to handle this. What other damage has the virus done to your system? Can you restore to a previous state? Also note that some viruses can hijack your virus software, preventing you from updating the virus software (typically redirecting you to an incorrect site, and blocking access to the correct site).

Csrss.exe is a core Windows process. Although there IS at least one malware program which masquerades as this program, in Windows, it is the Client/Server runtime System (the client side version of Win32.sys). This process cannot be ended from the Task Manager.

See here:

http://support.microsoft.com/search/default.aspx?catalog=LCID%3D1033&query=csrss.exe&mode=r

for additional details.

There are several versions of this TROJAN listed on the startup programs database here http://www.sysinfo.org/startuplist.php There is also a legitimite csrss.exe process which is a part of windows. Proceed with caution! There is a super duper program called process explorer available as a free down load which will allow you to kill it. Just google process explorer and get it from a legimite site. I recomend MajorGeeks.com. You can kill it with process explorer then delete it but as I said proceed with caution. MajorGeeks.com has a host of experts which will help you with this problem. They are working free in their spare time just for the fun of it so be nice!

Client Server Runtime Process = CSRSS.EXE y have 3.

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It`s a trojan?... A Trojan of Microsoft

yesterday i noticed my internet connection had slowed considerably, checked processes and noticed i had 2 items called csrss.exe in my processes list. when i tried to end the process my comp crashed. Looked around a bit, tried Malwarebytes Anti-Malware and it seems to have fixed it=)

http://www.malwarebytes.org/mbam.php