Firstly It is a malware..
Steps To Be Followed
1)Open Task Manager Press { Ctrl+Alt+Del} Select Processor Tab
2)Check For Svchost.exe Processor.The processor will be tagged under 4 Usernames
System,Local Services,Network Services & Username for Ex Administrator
3)Delete Svchost.exe processor that is listed under username
4)Then Start ->Run Type C:\heap41a press Enter.{ It is a hidden folder} Delete all files under this folder {Shift + Del}
5)Start -> Run Type "regedit" press {Ctrl +f} type heap41a, You find under "c:\heap41a\svchost.exe" and "c:\heap(Some numbers)\std.txt"
6)Close registry and restart the system .Now u can browse Orkut site
Cheers....