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June 23, 1997

Have you lost your AutoRun capability? Here's a simple fix

The Windows 95 Registry continues to be a fascinating subject for readers far and wide. I often hear tales of weird, irreproducible Registry changes. Now I have an example that seems to have been diagnosed by a reader and even has a fairly easy fix.

Mark Ottaway sent me his description of this behavior. Because he's done such a good job of describing it, I'll let him tell you about it in his own words:

"Windows 95B appears to be slightly more vulnerable than its predecessor to slight damage to Registry settings when crashes occur during programs that require frequent CD-ROM access.

"I know of a number of Win95B users who have suffered system damage (admittedly minor) because of a crash in the middle of using a CD-ROM program. The most common complaint is that the AutoRun facility of Win95 then suddenly stops. CDs still work perfectly well but will no longer run themselves using the Autorun.inf information on the CD -- they have to be manually started each time.

"Although this is a minor irritation, it is an irritation nonetheless -- especially for frequent CD users. Users have been forced to either completely reinstall Win95 or restore an old Registry backup and try to remake all the changes that may have occurred since that backup. Neither prospect is particularly appealing to most users.

"After a time-consuming analysis of the problem, I have hit upon a simple fix. The damage has been done to an important Registry key: NoDriveTypeAutoRun in HKEY_USERS\.Default\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer. This key controls the action that is taken by Explorer upon notification from the CD-ROM drive that a CD has been inserted (as long as Auto Insert Notification is turned on for the hardware in System Settings for the CD-ROM).

"To correctly autorun any inserted CD-ROM (and coincidentally to display the AutoPlay menu option when right-clicking on a CD-ROM icon), the value of NoDriveTypeAutoRun should be hex: 95 00 00 00.

"I have found that all errors of this type have been caused by corruption of this key's value. Editing the key and inserting the correct hex value, followed by a reboot, consistently fixes the problem."

To change this key to the proper value, run RegEdit.exe. In the window that appears, click the plus sign to the left of HKEY_USERS. Then keep clicking plus signs until you drill down to the Explorer folder at the end of the list of Registry keys mentioned by Ottaway. (Notice the period at the beginning of the .Default key.)

Select the Explorer folder, then right-click the NoDriveTypeAutoRun key in the right pane. On the context menu that appears, click Modify. Change the value to hex: 95 00 00 00.

Of course, this exercise doesn't explain why this Registry key (and perhaps other obscure Registry keys) is changed to a different value during a system crash.

Because I can't induce any of my various PCs to crash and reproduce this behavior, I can't test it to see what exactly might be happening.

In the meantime, I'd like to hear from other readers who have lost their AutoRun capability. Try the procedure described above and let me know if it restores the capability to your system.

This work-around for CD AutoRun problems may yet shed light on some other hidden workings of the Win95 Registry.

Brian Livingston is the co-author of Windows 95 Secrets Gold and four other Windows books (IDG Books). Send tips to or fax: (206) 282-1248.

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Copyright © 1997 by InfoWorld Publishing Company


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