A partial Summary of fixes posted for Zune not Recognized (non-driver issues)
0. Microsoft Links:
Zune Device Sync Diagnostic Tool
http://www.microsoft.com/downloads/details.aspx?familyid=F872E08B-27A2-4E1E-A0FE-862E4D6B901F&displaylang=en
Zune Media Collection Reset tool
http://www.microsoft.com/downloads/details.aspx?FamilyId=86B2A33D-9BF8-45F6-89FF-B9A6236AA37D&displaylang=en
KB 944909: Zune is not detected by your computer or the Zune software
http://support.microsoft.com/kb/944909?sd=zune
KB 940705: Troubleshoot sync issues
http://support.microsoft.com/kb/940705?sd=zune
Zune Forum, Top Support Links
http://forums.zune.net/7171/ShowPost.aspx
1. Log out other users on the system / Reboot.
(Zune software is profile aware: if loaded by a another user, loading Zune as you will carry over THEIR settings,
preventing a sync with your Zune, which will be greyed out.)
2. Vista / Windows 7: With the Zune disconnected, Run Zune software as Administrator once and connect Zune player.
It should run fine as user thereafter. [right-click on the zune icon (shortcut) and select the 'run as admin' option.]
3. Re-enabling the "Windows Mobile-2003-based device connectivity" service
4. Reset Zune player: Hold down the back button, then press on the upper part of the finger pad (at the same time).
After a second or two, the device will turn off, then come back on.
Some report success resetting the Zune while disconnected from the PC;
others report success doing the reset while the Zune is connected.
Yet others report success only after allowing the Zune battery to completely drain by letting sit for 2+ weeks.
5. Change the Power settings for USB devices / Zune to disable allowing the system to turn the device off to save power
and/or disable USB selective suspend setting.
6. Add the Zune program folder and all sub-folders as exceptions/exemptions to the anti-virus software
so that the a-v software doesn't prevent the registry and device scan performed by the Zune software.
7. Uninstall non-standard USB devices (e.g. PS3 controller drivers)
8. Uninstall / reinstall / upgrade software and/or firmware.
Some users get REAL aggressive and manually delete all Zune related files and registry keys after an uninstall.
Your results may vary from the reported 'fixed' by some users if you manually edit your registry!
9. Scan for trojans / viruses.
Some trojans and virus cause driver problems and/or affect registry access.
Some users have posted re-install Windows as an alternative. Yikes!
10. Replace the sync cable
11. Add a USB 2.0 expansion card to the system.
(Zune player will sometimes not reliably sync to unpowered USB hubs or over USB 1.0.)