What is it?
Real Time Virus scan (Symantec Security) - rtvscan.exe
What does it do?
Symantec Internet Security Suite is taking Norton AV to another level and scan the files as they enter your system instead of the usual scan right after they hit your system. You should not end this process if you have it running.
You'll want to keep an eye on this google search for any known viruses. The normal location of this file is C:Program FilesSymantec_Client_SecuritySymantec AntiVirusRtvscan.exe