Vertical Line on Monitor

I have a Dell 2405FPW flat-panel monitor.  About a year after I bought it, it developed a vertical line on the right-hand side of the screen.  It started as a thin red line, then turned into a white stripe about a half-inch wide.  Then, after a while it went away, so I didn't do anything about it.  Later, it came back, and grew to be about an inch wide, with colorful lines along the right edge.  Eventually it expanded to about two inches, half fairly solid and half sometimes solid and sometimes translucent. 

I had serious problems with my computer and after I bought an extended warranty, Dell replaced it with an Alienware Aurora.  When I hooked the monitor up to the Aurora, the stripe had gone away.  But after a couple of months it came back.  Here's what it looks like now:

and here's a close-up:

Is there anything I can do about this?  Is it covered by the extended warranty I bought?  Thanks for any help.

Regards,

Jim Crutchfield
Long Island City, NY