Q: I have a vertical line in the centre screen of my g5 mac - any help please ?

If the line is permanent, it's a display problem. As you have an iMac G5, it's possible that Apple refuses to repair the display, apart that it's a very old Mac

You may have a problem with the video chip.

Here is how to tell...

  Shutdown your machine.  Hold down the shift key.  Poweron.  Bootup will be longer.

    Wait awhile while you harddrive is being checked.

  An article on how to boot into safe mode.

    http://support.apple.com/kb/ht1455

Runs OK in safe mode...

Running in Safe mode leaves out some video drivers.  Which results in your machine not using advanced video hardware. As luck would have it, you can run the safe mode video drivers in normal mode.

Here is how:

https://discussions.apple.com/message/16057567#16057567

Look through the above thread.  See the second page.  You don't have to read through the first page.  Just go to the part where I try a solution that works.

Summary of G5 problems. Includes instructions on a hardware fix for the brave at heart:

See -Rotten Apple- articles in both of these threads.

https://discussions.apple.com/thread/4023152?tstart=0

https://discussions.apple.com/message/18700825#18700825

Robert

There were several Mac models with flat panel displays that had bad displays. Most had serial numbers beginning with "W8"---the code for one specific factory. This affected PowerBooks as well. If that's the case, the rest of the computer is probably fine.