Written by Topher Kessler
MacFixIt Answers is a feature from MacFixIt where our editors answer questions e-mailed to us by our readers. This week we have a question about scrambled video playback on an iMac G5 that results in a hard crash of the system, and a question on connectivity options for printers that rely on AppleTalk, given the possibility of Apple removing AppleTalk from OS X in Snow Leopard.
MacFixIt reader "Douglas Parker" asks about crashes that show scrambled video whenever he plays media files on his G5 iMac:
"When I say the video is scrambled, the entire screen goes into a herringbone
pattern. The computer locks up and I am forced to shut down the computer by
pressing the power button. I have tried logging into from remote computer in
SSH and doing a shutdown from that point, but the computer is in a state
that doesn't give me the remote login.
The computer runs fine in SAFE MODE. Currently it has been running 1 day, 9
hours without an issue in safe mode. All I am using it currently is to
respond to your e-mail. It also runs in Single User mode without issue. Prior
to rebooting in Safe Mode I was in Single User mode for several hours
looking at log files to determine what could be causing the problem. I did
get a notice of a Perian update but had not downloaded and installed that
update. It has been several months since I updated Flip4Mac."
Since the computer boots and functions fine in Safe Mode, this problem sounds like a driver conflict, which could stem from a corrupt system driver file to a problem with how other software interacts with the driver. In this instance, a possible culprit could be the "Perian" plug-in or other multimedia extension, especially since the lockups happen when playing media files; however, it could be corruption in a QuickTime component as well.
To test this, remove all files from the following folders and restart the computer:
Additionally, see if any third-party component has been placed in the /System/Library/QuickTime/ folder, and remove that as well, reboot, and try playing media again. You should also try using another media player that does not use QuickTime, such as VLC, to see if the problem is with QuickTime or perhaps with another driver such as the video card drivers.
If the computer runs fine after this, then move the components back into their respective folders one-by-one and restart and play media files after each.
MacFixIt reader "Bruce Klutchko" asks:
"I have a HP Laserjet 4M that is working well on OS X 10.5.7. It has
been reported that Snow Leopard will drop support for the AppleTalk
protocol, so I'd like to know if there are drivers that will support
a USB-Parallel cable with this printer. I can successfully use this
cable with the 4M with a PC laptop from my office using its
'Virtual USB Printer' driver. Is there something similar for the
Apple may very well remove AppleTalk from OS X in Snow Leopard; however, we will not know for sure until the final release. Still, assuming it does, there are some possibilities you can look into. The first is to try the latest driver from Hewlett-Packard, to see if any other protocols are supported. The link to the latest driver is here.
While AppleTalk may be used for your printer, the printer also supports other protocols (ie, IP and SMB), which you can try setting up to work with your printer. Do this with the driver mentioned above, as well as with the Gutenprint drivers that are included with OS X. Additionally, the USB-to-Parallel adaptor may also work. These have functioned properly in the past for me, but success will be device-specific.
If worse comes to worse, you can get a third-party print server that can connect to the printer via its local Parallel or Serial connections (or even AppleTalk), and then use a more modern protocol to send jobs to the print server, which will then relay them to the printer. Here are a couple of examples of cheap parallel print servers, which may work: 1, 2.
There are a variety of similar print servers out there, and they can be a cheap alternative if other connectivity options do not work.
Topher has been an avid Mac user for the past 10-15 years, and has been a contributing author to MacFixIt for just over a year now. One of his diehard passions has been troubleshooting Mac problems and making the best use of Macs and Apple hardware both for family and friends, as well as in the workplace. He and the newly formed MacFixIt team are hoping to bring enhanced and more personable content to our readers, and keep the MacFixIt community going here at CNET. If you have questions or comments for Topher or the other MacFixIt editors, feel free to contact us at http://www.macfixit.com/contactResources