Trojan csrss.exe

Hello Leslie,

We understand your concern but we request you not to believe any popup that is appearing on your PC to be legitimate.
In order to check with this threat issue, we have sent you an email with further instructions to be followed to get our additional support.
Please check for the email on spam or junk folders if it is not present in the inbox.
Thank you.

I got a call from Dell because my computer was pinging them.  The event viewer showed that I was infected on 12/21 and the scan showed csrss.exe.

First, how come AVG doesn't know about this?  Also, how do I get rid of it?  I've searched the internet, and just don't see a solution that I'm happy with.  I'd appreciate any help anyone could give me.

Hello Leslie,

We understand your concern but we request you not to believe any popup that is appearing on your PC to be legitimate.
In order to check with this threat issue, we have sent you an email with further instructions to be followed to get our additional support.
Please check for the email on spam or junk folders if it is not present in the inbox.
Thank you.