BSOD caused by... bad USB hub!

I’ve seen this kind of thing before – a computer whose problems are caused by the stuff that’s plugged into it – but this one almost fooled me.

A customer called with a computer that would BSOD and instantly restart early in the boot process, but would run just fine in Safe Mode. I was hesitant to take the job, but the guy agreed to pay even if all I did was pronounce the machine dead. (Hey, it’s all about nine-tenths of a Benjamin, baby).

I selected “Disable automatic restart on system failure” so I could read the blue screen. It pointed to a driver.

I started it in Safe Mode and checked out the driver file. It looked OK: it didn’t have 'zero' file size, was last modified in 2004, and was apparently for the guy’s Creative Webcam. I renamed it anyway, thinking it was probably corrupted or infected with some strange virus.

I restarted the machine, and it ran fine, except of course the Webcam didn’t work.
I reinstalled the driver… and the computer flashed up a warning about excessive power drain on a USB port, and blue-screened!

It turned out that the guy had three items plugged into an old Radio Shack powered USB hub which had partly failed: it wasn’t delivering power to the connected devices, and they were pulling all their juice – over half an amp -- through it from the single USB port to which the hub was connected. This was all it took to crash the computer, and Dr. Watson blamed the Webcam driver. Moving the camera to the only remaining USB port on the front of the PC fixed the problem.

Reminder (to myself, at least): unplug all the peripherals when troubleshooting weird problems. There are a few questions about powered vs. unpowered USB hubs on the MCDST test, but I never expected to run into it in the field.

 

thanks for the tip. I have a laptop with a bunch of usbs hanging out... I shuold be careful.

 

bad usb hubs can be the underlying problems for alot of small things like this, including but not limited too BSOD. I've had devices get screwed up from bad usb power due to design flaws, powered usb hubs from over seas etc. last year my favorite cellphone (a v710 old but did everything i wanted it to do) simply die after a night of it being left to charge over a usb plug that was plugged into a flaw'd usb hub. the phone was being given excess power and it eventually burnt something inside of it out, i only know its the hub's fault because a replacement e815 (which is protected from such weird power things) would say unable to charge while being plugged into the exact same hub/cord.