VNC which means VIRTUAL NETWORK COMPUTING is a software which allows you to do Remote Assistance / Remote Desktop. The other user must have VNC also installed on his machine. VNC is an Open Source software, completely free of use.
Run the server
A password will be needed from the person who will help you
Send him your IP Address to give him access to your machine remotely.
When doing so, the other user will have access on your pc! He will navigate your OS and fix the error you got!
It is available for a very large number of platforms. In particular, the client may be a simple java applet in a browser!
A person running Linux may thus act upon your system though you're running Windows and vice versa.(platform independent )