Cursor Keys (arrow keys) do not work when answering email

I have a new Latitude E6420 laptop. Vast improvement over my 5.5 yr old T60. It's new and relatively clean except for Microsoft Enterprise. I received personal email from Earthlink.net and usually view and reply to my personal mail messages via "web mail" directly on Earthlinks web site rather than using Outlook.

When replying to email on Earthlinks web mail application I've noticed the cursor (arrow keys) go inert and do not work. The only way I can move the cursor to a different location in the reply is to use the mouse and the cursor does not blink.  I can not move the cursor backwards to correct a typo for example or up or down to change lines. I am wondering what gives? Is it a settings issue in the websites options?; a settings issue in my Explorer browser or maybe a graphics card or driver issue?; I don't have any idea where to start. Otherwise this laptop with an i7 processor, 8GB and SSD drive blows me away. I hate to have to stoop to asking one of the MIS guys/gals in the office for help since they look at you like you are an idot. 80% of the time the solution leaves the machine worse than it was with the original problem.  I believe this laptop has both an onboard Intel graphics processor packaged with the CPU as well as a discreet NVIDIA card. I think the settings are still at the original factory defaults and Win 7 or the software is managing how graphics are processed depending on function and demand but I'm really not a guru in that area.

Any suggestions would be very helpful. BTW those cursor keys are working fine exactly as expected in this post. They go inert when responding to Earthlink email. Open to any suggestions or ideas about where to look for a solution to annoying problem.