Solving USB Problems
Problem | Possible Cause | Solution |
External device | The operating system | Reduce the number of |
connected to a USB | limits external devices | connected external USB |
connector does not | connected by USB to | devices to no more than |
work | two tiers which can | two hubs on the first tier, |
| include no more than | and no more than one |
| two hubs on the first | keyboard and one |
| tier and no more than | pointing device on the |
| one keyboard and | first or second tier. |
| one pointing device |
|
| on the first or second |
|
| tier. |
|
|
|
|
External device | During startup, only |
connected to USB | two tiers are |
connector does not | supported by the USB |
work during startup | connector. These tiers |
(before Windows 95 | can include no more |
loads) | than two hubs on the |
| first tier and no more |
| than one keyboard |
| and one pointing |
| device on the first or |
| second tier. |
Use the external device only after Windows 95, Windows 98, or Windows 2000 Professional has loaded.
Reduce the number of connected external USB devices to no more than two hubs on the first tier, and no more than one keyboard and one pointing device on the first or second tier.
External devices in | An unpowered hub is |
lower tiers do not | connected to another |
work | unpowered hub. |
Use only powered hubs.
Make sure that all unpowered hubs are immediately preceded by powered hubs in the USB chain.
IMPORTANT: External USB keyboards will not function until the operating system has been booted.
