More on problem-causing USB hubs under Mac OS X 10.4.x

Today we continue coverage of an issue where malfunctioning USB hubs can cause a wide variety of problems under Mac OS X 10.4.x, including problems launching applications, kernel panics, stalls in system responsiveness, and more.

In many cases, these hubs work without difficulty under previous iterations of Mac OS X (Mac OS X 10.3.x, for instance), but exhibit complications under Mac OS X 10.4.x. As such, it would appear that Mac OS X 10.4.x (Tiger) is more sensitive to issues generated by these devices.

As noted yesterday, what appears to be happening in these cases are stalls or other errors in the queries that Mac OS X applications, or Mac OS X components send through the USB framework. When the problematic hub is encountered, stalls or complete freezes can occur.

MacFixIt reader Wayne describes his case, in which a problematic USB hub caused issues with iPhoto when attempting to communicate with a digital camera:

"I have a D-Link DUB-H4 powered USB 2.0 hub which, prior to upgrading to Tiger, worked just fine on both my PPC G4 Sawtooth and my G5 Dual 2.0 Ghz. However, after installing Tiger, iPhoto began to stall when trying to communicate with my Casio digital camera. In effect, uploading photos became impossible. At first I thought this was a bug in iPhoto, which was also upgraded at about the same time. However, on a hunch, I tried connecting the camera directly to the USB port on the G5 (I've since retired the G4) and all the problems went away. I still use the D_link hub for connecting a few other devices but, since your article, now I'm starting to wonder if I should. Thing is, if it's the hub, how do I find a "good" one? The D-Link wasn't cheap and, as I said, it worked fine prior to upgrading to Tiger... So, what's the secret ingredient here? Seems to me like something changed in Tiger that brought out this behavior."

These issues can also affect USB and USB 2.0 PCI expansion cards, as evidenced by the following report from one MacFixIt reader:

"I have a PowerMac G4 with 1 GB of RAM running Mac OS X 10.4.2. The one PCI card I have installed is an off brand USB card that has been working for years. Until the latest Tiger release. I get at least 10 kernel panics a day with this card installed. It took me a week to figure out the card was causing it. Once I took the card out all kernel panics have ceased."

Kami Shkval describes some issues with mouse behavior that were solved by eliminating a problematic USB hub. These reports are typical, with users reporting erratic behavior form USB mice and keyboard when used in conjunction with a hub that is on the fritz.

Kami writes:

"Earlier in the year, I used an Iogear USB 1.0 hub with my PowerBook, but decided to change to a faster hub to take advantage of the PB's USB 2.0. I purchased the Iogear USB 2.0 UH-275. Around that time, my normally reliable Microsoft Trackball Optical started acting odd, as if the cursor were slippery. I couldn't select and drag, the mouse cursor got the jitters, clicking sometimes didn't do a thing, etc. If I tried to move an email from the Inbox to a subfolder, the mail would just drop off the cursor and I'd have to look for it in one of the folders along the way. I had to resort to using the trackpad. I bought another trackball, I bought Tiger and installed it, I cleaned the mouse repeatedly, all to no avail. Most odd of all, I started seeing the little text boxes you get when you mouseover a blog or newspage, and they would just appear on the desktop. They would show through any work I was doing and I'd have to move the cursor somewhere else to make the text vanish. Finally, I called Apple Tech support. After disconnecting the hub, and just plugging in to the USB 2.0 port on the PB, everything worked fine... no text boxes and the mouse came back to life. I checked the Iogear web site and a brief announcement is given on the support page that Iogear USB 2.0 hubs do not support trackball mice. Sure as heck wish they'd noted that kind of thing more obviously. I never had a problem with the USB 1.0 hub and would not have given it away."

So which USB hubs are prone to be problematic? If you are using a hub that appears to be unproblematic, please drop us a line at late-breakers@macfixit.com, indicating the manufacturer if possible.

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