stephan_mc,
Well, I don't know either what the problem is. I can only suggest some
steps that may or may not take care of the issue. Since the drive works with
the Vista DVD, it's obviously working.
Here are some things to try: In Device Manager, review the Properties of
the drive to confirm that Vista shows it to be functioning properly. Note
any indications of a problem.
If it appears to be working properly, right click the drive and select
uninstall. For that to take effect, Windows must reboot. The idea here is
that when Windows boots, it will reinstall the drive and fix any problems.
Consider a cleaner disk for cleaning the laser pickups in the drive. This
may be a long shot, especially if the drive was functioning before the
installation of Vista. However, it's best to cover all possibilities.
Vista records errors in a report. Review the report: Start > All Programs
Maintenance > Problem Reports and Solutions. Peruse the report to note any
errors and focus on any suggested corrective action to take.
Place a disk in the drive, and then use Windows Explorer (Start >
Accessories) to see whether you can access the drive. Note any errors given
when you do this.
Check Disk Management (right click Computer, formerly My Computer, and
select Manage, and then select Disk Management. Confirm that the drive
appears in Disk Management and is assigned a drive letter. If it has no
drive letter, you can assign one.
Consider replacing the drive. I see no reason why it doesn't work.
Others may have additional ideas. Post back on results.