I have a Sony KDL-46XBR8 Television and it intermittently has vertical lines on the display.

Vertical lines indicate a screen going bad itself instead of the T con board.

Defective display panel.

Check the main filter capacitors at its power regulator board. Replace if found bulged or damaged. Replace all secondary side supply rails' filter capacitors too. The fault is with damaged electrolytic capacitors at the power regulator board itself.

I have never heard of a warm-up problem on a digital television. Unlike the old CRT TVs and monitors, digital panels don't have to warm up. I would go with the TV repair persons assessment that you've got a bad panel.

It is the lcd panel failing, the same as mine. See link
infofrobetterbuys.blogspot.com

It's a connection inside the TV that's faulty. It could be as simple as reseating the ribbon cables that connect the control board to the glass display. Or it could be that the fault is on the board and needs to be replaced. The fact that the problem comes and goes should tell you it's fixable.

http://www.avforums.com/forums/sony-owners-forum/1165140-faint-lines-kdl32s5500.html

I have also experienced the same problem on two occasions, but my Sony TV KDLV3000 has actually been backwards and forwards on three occasions to be repaired. I have had a new control unit and will be having a second screen replacement shortly. I have contacted my local Sony Centre and they have stated that they will only replace the TV if there are THREE IDENTICAL faults.

COME ON SONY CENTRE GET YOUR ACT TOGETHER AND TAKE A NOTE FROM JOHN LEWIS THERE CUSTOMER CARE IS SECOND TO NONE.

Not sure I'll buy a Sony again after this experience having been a loyal Sony customer for a number of years, will probably look at a Samsung or LG next time.

It can be either the LCD controller board, or worst case the LCD panel, symptom of bad panel is vertical lines from the top to the bottom of screen, and it will get more lines as time goes by.
http://www.shopjimmy.com/catalogsearch/result/?q=Sony+BRAVIA+XBR+KDL-V32XBR1+

sorry but you damaged the screen. Nothing short of replcement.

I had a similar problem where the screen went to a pink shade periodically. Sony sent me a memory stick, with download instructions, that fit into one of the back ports. The problem has gone away. It was a software correction.