MacBook Special Report: Vertical lines appear on screen during startup

CNET staff

Sept. 2, 2009 7:25 a.m. PT

3 min read

Some MacBook owners have reported an issue where a distorted screen appears during startup, characterized by a series of vertical, multi-colored lines. Usually the startup process freezes at this point, necessitating a restart.

Below is an image of the problem:

MacBook screen distortion

One reader writes:

"After restart the screen goes gray then random vertical lines draw on the screen.. trying to restart by pressing the start button for several seconds doesn't help... the MacBook just turns off then back to the vertical lines.. took out the power plug but that didn't help either... the only thing that got the MacBook back to normal was taking the battery out then back in. After that the MacBook restarted normally."

In some cases, users are able to temporarily work around the problem by resetting PRAM, accomplished by holding down the Command, option, P and R keys simultaneously during startup.

Bad RAM does not appear to be a factor in most cases, with users swapping out modules and still experiencing the problem.

It appears that, for many users, this problem did not appear until updating to Mac OS X 10.4.7. As such, some are choosing to revert to Mac OS X 10.4.6, per the instructions in this tutorial.

One reader writes:

"Shortly after installing 10.4.7 (initially via software update and later as the combo update), my MacBook and that of several others have developed an odd malady. Upon reboot, the screen goes completely white, then gradually more and more numerous, colored, vertical lines appear on the screen. The machine never reaches the desktop or login screen. Pressing the power button to force shutdown and restart does not clear the problem. Zapping PRAM temporarily restores normal function, but a reboot later may still result in the white screen with vertical lines.

"Some speculation is that the NVRAM has been affected by 10.4.7 and this is consistent with my experience. I initially only had a sudden shutdown problem after awakening from sleep. I had not see the white screen with vertical lines problem despite restarting the machine. That appeared after I tried resetting the PMU and zapping PRAM.

"For now I've reverted to 10.4.6 to see if my MacBook becomes stable again. Prior to installing 10.4.7, my MacBook had worked solidly for weeks without any sudden shutdowns or screen of vertical lines issues. There may be something awry with the 10.4.7 Intel update."

Another MacFixIt reader, Matthias, adds:

"I also have the 'vertical lines' problem on my Macbook. It started after I applied the 10.4.7 update and seems to appear on every restart now. Only solution I found is resetting the PRAM.

"I had originally updated using Software Update (with the re-released 10.4.7 update, I updated on July 1st). Then everything worked fine.

"Afterwards I installed the Combo updater because I wasn't sure if the Software Update version was o.k. (because the somewhat strange re-release), but this caused the "vertical lines" problem. My MacBook would only start up after a P-RAM reset.

"Now I applied the Combo updater again and everything seems to be fine again: I restarted several times, and I did not see the vertical lines again."

MacFixIt reader Chris writes:

"I too have had this problem with my white 2Ghz MacBook, ever since I updated to 10.4.7. I'm not saying that 10.4.7 is the definitive cause of this, but it never happened to me before. Every time I've shut down the MacBook and powered it up later, I have to do a PRAM reset in order for the display to come online again. Apple really dropped a bollock on this one."

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