Lenovo Laptop and dual monitors - extended monitor has purple horizontal lines

I have just deployed a freshly-imaged Lenovo T420s laptop (win7x64)  to a user with dual external monitors.  The laptop sits in a docking station and the lid to the laptop remains closed - only external monitors are used when docked.  Immediately after setting up the user's two external monitors, I noticed something odd - the main monitor is fine, but the secondary, extended monitor has flashing purple horizontal lines from top to bottom.  

Additional info:

1.  When I switch the main monitor in Windows to be the secondary, extended monitor the lines follow the monitor - the problem happens on whatever monitor is designated as the extended monitor.  
2.  When I put my own laptop in the user's docking station, the problem disappears....confirming the issue is with the user's laptop and not the monitors, cables, power, etc.
3.  Updating the graphics card driver (Intel HD Graphics Driver 3000) on user's laptop from Lenovo's web site did nothing - the horizontal lines remain.  
4.  Changing resolution settings on extended monitor did nothing - horizontal lines remain.
5.  I compared the display and driver settings on the user's laptop to my own laptop and the settings are identical.  

I'm normally pretty darn good at diagnosing these types of problems, but this one has me stumped....any suggestions are appreciated!

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Maybe a photo of the problem display would help? Have you made sure all the firmware, BIOS and all the drivers are up-to-date, not just the Graphics driver? Is the OS fully updates?

Does the same thing happen If you boot the laptop using a LiveDVD, like PCRepix?

JohnBusiness Consultant (Owner)Commented:
Many Lenovo ThinkPads have a Monitor.inf  that you can download from the Lenovo Support site. Make sure you select the  correct T420s download page(s), download the file, install it according to the instructions, shut down the computer, start it up again and test.
"Updating the graphics card driver (Intel HD Graphics Driver 3000) on user's laptop from Lenovo's web site did nothing - the horizontal lines remain. "

Replace the graphics card.

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JohnBusiness Consultant (Owner)Commented:
That means replacing the motherboard on a ThinkPad
Yes, that is true.
It is cheaper to replace the laptop...
The data can be backed up or the hard drive can be cloned or the hard drive can be used in a same model laptop found cheap on eBay.
djfox1963Author Commented:
Thanks for the suggestions, all, and sorry so late to respond.  This turned out to be a problem with the integrated graphics card on the laptop and the laptop was replaced.  I appreciate the suggestions.  Thanks!
That is what I suggested:

2015-09-28 at 01:53:43ID: 41008055

"Replace the graphics card."

2015-09-28 at 02:34:51ID: 41008109

"It is cheaper to replace the laptop..."
I've requested that this question be deleted for the following reason:

Not enough information to confirm an answer.
The OP confirmed that my suggestion was the correct solution by posting:

2015-10-01 at 03:51:09ID: 41018750
"the laptop and the laptop was replaced"

My solution was correct:

2015-09-28 at 02:34:51ID: 41008109
"It is cheaper to replace the laptop"

The Op has abandoned the question by way of not awarding points,  but confirmed that my solution was correct.

Suggest a forced accept with "A" grade to my solution:
2015-09-28 at 02:34:51ID: 41008109
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