Placement of curser gets messed up on large file edits. [1]

When i edit any large (50 lines or more) files with pico or nano, on any system using the xshell client, I have a problem where the curser will start to jump around the screen and mess up the way the editor interface looks.

To further research your problem, please send us the following information:

1. Screenshot of the problem.
2. Vendor/version of the remote host.
3. Terminal type. Send us result of the following command.

# echo $TERM

4. Xshell version.

Thank you for your cooperation.