Connecting two USB 6509 devices. Both devices use the same USB ROOT HUB. Only one is detected on startup?

[RAPTR1]

We are using two USB 6509 devices, Measurement Studio v8.6, DAQmx v9.3.5 drivers, MAX v5.0, and Windows 7 32-bit desktop.  The devices are externally powered before and during.  Both USB 6509 devices pass through the same USB ROOT HUB.  [Infact, all USB devices appear to run through the same HUB]

#1 When we start Windows, only one device of the two connected devices is detected,

#2 After a reboot, both are detected; however, only one device passes the self-test in MAX,  The other device indicates a 50405 error code.  Reset in MAX does NOT clear the error.

#3 After a reboot again, finally both are detected and both pass the self-test in MAX.  Both work well at this point.

How do we detect both USB devices automatically, without error, when starting Windows the first time.  [This application is intended to be started by an operator each day]

Note: I can connect both to my Laptop (same NI configuration except 64-bit / Generic HUB) and both connectsand run the first time.

[SnowMule]

Try a different computer model.
We have tons of problems with the Dell T-series (3400's, mostly) but the same system works great on an optiplex. 
In my experience, chipsets and drivers are to blame.

It's kind of a long shot, but might be worth the time... different USB hub.  I've had better luck with the Startech 4-port hubs than I've had with the cheaper consumer-level stuff.

[RAPTR1]

1) The desktop hardware is Advantech industrial rack mounted.  The laptop is DELL Precision M4600.

2) We tried other USB ports, but all went through the same USB root hub.  How do you redirect a USB port to a different USB root hub?

3) If the Startech 4-port hubs connects to this same single USB HUB on the desktop, would I not have the same issue?

Thank you!

[SnowMule]

The problem could be with the hub itself, and how the hub and root hub on the PC interact.

Or it could be the root hub on the PC.

If it's the former, changing the USB hub may help.
Latter, only way you're going to change things is to change the computer. A PCI-USB card may be worth a try.

Do you have to go through a hub, or could you connect both devices directly to the computer?