Random USB devices not detected

USB is iffy at best, always was. A 7 port ⚠ hub is bound to have conflicts because the underlying technology is second rate. Live with it.

I think the problem with USB is the 250+ item limit is pure theory. 7 devices hooked up at once, powered hub or not are too many devices. Apple did not get rid of firewire. The MB Pro has it, Mac Pro has it, iMac has it.

Since I also have 7 port hubs and have no problems, I know it can be done with stability. Your problem might be with the hub, a cable, or one of the devices. I'd start by plugging the mouse into the keyboard and the keyboard directly into the computer. Then I'd connect the scanner to the computer and remove the hub altogether. If everything is stable, I'd reconnect the hub and connect the scanner to it. In other words, basic troubleshooting 101. Isolate and slowly bring things online until trouble develops.

There are three possible issues: in ascending order of likelihood: computer USB port, keyboard, hub. Have you tried the keyboard connected directly to the computer? If the keyboard is rock steady connected directly we can be pretty sure it is the hub.

I have a selection of hubs. At home I have a Belkin - the one with two ports on top and the rest in back. Don't have the model number. Here at work I have a cheap generic - USB-WARE is what it says on back. I tend to stay away from D-Link. They burned me on a WiFi router and I'm voting with my dollars.

I understand why you are using it, I have the same kind of setup at work. But why waste time and money buying a new hub if the problem is your keyboard? I've been buying lots of Belkin gear myself.

It probably means that you are using some gear that has badly written drivers for use with current versions of OSX, Damien. You might want to check the websites for the equipment that you are using to see if the drivers have been updated for use with recent versions of Leopard.

Cheers

Rod

Have you considered that it might be a software conflict?

When I first began using Quicken for Windows, iTunes would not work properly. It would rip only one or two disks, and would not fully eject them (only about 1/4 of the disk would eject, not 1/2). The problem corrected itself after an upgrades to either iTunes or Quicken, I don't know which. I traced the problem to iTunes/Quicken by unloading all the software (actually, as I recall, an "archive and reinstall"), then reloading and checking iTunes' operation after reloading each application (there was never a problem running Quicken). iTunes worked fine with each re-install until Quicken.

More recently, the software that runs my USB Colormunki (a device for calibrating a monitor and establishing a printer color profile for photographic printing) will not recognize the device, no matter how or where it is connected, although the MacBook Pro confirms that it is connected (Apple/About this Mac/More Info/Hardware/USB). BTW, the device did work one time. The device works on other Mac's, but other samples of the device don't work on my Mac. I have been through numerous uninstalls and reinstalls, and been over the problem numerous times with both Apple and Xrite (developer of the Colormunki) Tech Support.

One of the things I am implying by going through the Apple/About this Mac/etc. menu item is that the "it" that doesn't recognize a (usb) device - the Mac OS or the software that allows the device to function - needs to be specified. At least it needed to be in my situation with the Colormunki.

Fred

I've had exactly the same problem, with my keyboard, mouse and (Logitech) camera. They've all been plugged directly into my 2008 Mac Pro, so there's no hub issue. Sometimes I can get one back by forcing a sleep/wake cycle.

Let me state in different terms what I wrote in my previous message. In order to try to determine if a USB port is faulty, you need to go to the Apple Menu/About This Mac/More Info..../Hardware/USB and see if you can find your device. Having said that, some devices (such as a BlackBerry connected to a USB port) might appear under a different heading. The BlackBerry appears in "Locations." If you find the device, my guess is the port is working properly, and the device also is working at least to some extent (assuming it is turned on if it needs to be ☺). The question of whether the port is providing sufficient power to the device is, I think, a different issue.

A common fix for problems with software and their devices is to uninstall and reinstall the application software. Sometimes uninstall software is provided by the vendor. Uninstall software also is available from third parties. With the Mac OS, it also is possible to uninstall software by moving it to the trashcan. The first and last methods do not necessarily remove all components of the application, however; I cannot speak for third-party uninstall software. Below are some instructions I received from tech support at one software vendor to ensure removal of most, if not all, of the components of applications, including those that might be missed by the aforementioned means of uninstalling. I have re-written the instructions to make them generic. Just be careful that you trash only the files that you intend to remove! Based on my experience, please note that there might be files in frameworks (or elsewhere?) that do not contain the name of the application; contact the software vendor's tech support if you are uncertain. This seems to be the exception, however. I hope this is helpful.

INSTRUCTIONS FOR COMPLETE UNINSTALL OF AN APPLICATION AND COMPONENT PARTS
Trash the following files:
1. "App Name" in Applications.
2. Files starting with "App Name" located in Macintosh HD/System/Library/Extensions
3. "App Name" folder located at Macintosh HD/Library/Application Support AND/OR Home Folder/Library/Application Support
4. "App Name" frameworks located at Macintosh HD/Library/Frameworks AND/OR at Home Folder/Library/Frameworks.
5. Any preferences containing "App Name" at Macintosh HD/Library/Preferences AND/OR at Home Folder/Library/Preferences.
Reinstall “App Name.”

Fred