AutoRun feature do not seems to work, why?

In some computers the AutoRun feature do not seems to work, why?


As mentioned before, all Windows since Windows 95 have the AutoRun technology built-in, but in some computers this feature can be disabled. Administrators can disable this features in client computers on a network for security reasons and some applications, for example CD burning programs, can sometimes also disable this feature. If AutoRun is disabled on a computer you can enable it by changing a value in the registry.

There is a value with the name NoDriveTypeAutoRun at the following
key:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorerthat probably is B5 (hexadecimal).

If that is the case, you can change it to the hexadecimal value 95 and then restart the computer. After the reboot the computer should have the AutoRun feature enabled again.

The NoDriveTypeAutoRun value contains a bit mask where every bit that is set disables a drive type. The default value for NoDriveTypeAutoRun is 95, giving the bit pattern 10010101. Bit number 5 enables/disables AutoRun on CD-ROM drives and as default this bit is cleared (zero). By setting this value to B5, the bit number 5 will be set (one) and the CD-ROM drive is disabled.

The bit pattern for B5 is 10110101.It's also possible to enable/disable AutoRun on other drive types than CD-ROM by clearing/setting other bits in the NoDriveTypeAutoRun value. For example it's possible to have AutoRun enabled for floppy disks.

In the table below you find some of the bits and what drive types they represent.

Bit 2 = Disk can be removed from drive (such as a floppy disk)
Bit 3 = Disk cannot be removed from drive (a hard disk)
Bit 4 = Network drive
Bit 5 = CD-ROM drive
Bit 6 = RAM disk

To enable AutoRun you must clear the corresponding bit.

You can read more details about enabling/disabling the AutoRun feature at the Microsoft page: Enabling and Disabling AutoRun.