I had a very annoying OS issue yesterday. It all started with the release of Visual Studio 2008 Beta 2. Unlike previous releases where a new Visual Studio usually meant a new .NET Framework (which also meant a new CLR) this time the CLR is the same as it was when version 2005 came out, the rest is just extra libraries in the BCL and a few new compilers. This does not mean that it wasn’t a lot of work to put these out, just look at the Linq goodness in the new compilers. But this also means there’s no* risk installing this beta on a production machine either side-by-side with Visual Studio 2005 or standalone (if you use Resharper, it works with 2008 too). Extra safety is provided by the Go-Live license and multi-targeting: you can use version 2008 to target .NET 3.5 projects, but also 3.0 and 2.0 (yay!).

Great stuff, I just need to update to the latest version of the CD/DVD emulator so I can mount the ISO image and I’m ready for the installation. Except that after I installed the latest Daemon Tools, there was no drive. Updated to the latest SPTD driver, nothing. Removed, reinstalled older version, again nothing.

Removed Daemon Tools, installed Alcohol 52%, still nothing. By this time I was really annoyed – every reinstall meant a restart because these apps have to add a driver for a virtual CD/DVD and by this time I have restarted the machine more than in the last year or so  – yeah, despite what Linux zealots think I generally never restart my Windows boxes. Tried with one more virtual CD/DVD utility that I remembered as the only one that worked on early Vista beta versions, still nothing.

By this time I exhausted all well know software CD/DVD emulators. Then I removed spare battery and slid in physical DVD-RW drive. It did not work.

Now we’re getting onto something. None of the CD/DVD drives worked including the physical one, so a setting in the OS somewhere must be blocking them all. The error I got for the physical drive was not informative but when I uninstalled it and let the OS (Windows XP 32–bit) rescan the hardware, I got a bit more specific error: Windows cannot start this hardware device because its configuration information (in the registry) is incomplete or damaged. Finally – so it’s definitely configuration related.

Google to the rescue, I found a post in a forum that nailed it: I had a leftover CD/DVD filter driver configured, but I removed the startup of the driver manually in the (most excellent) Autoruns because the software that used it was uninstalled long ago. The remedy is simple – just go to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318} and delete keys UpperFilters and LowerFilters (or, if you want to be on the safe side, rename them). Reboot and voila! All the drives are back.

*To be precise, there’s little risk, as installing beta stuff can always screw things up.