When you are running Windows 95 on a computer with an IDE (ATA) hard disk and controller that support Ultra DMA mode, the computer may stop responding (hang) while the hard disk is being accessed.

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This problem can occur if there is a hardware error while data is being read from the hard disk. When such an error occurs in Ultra DMA mode, the Windows device driver does not successfully recover from the error and retry the operation.

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Microsoft has confirmed this to be a problem in Microsoft Windows 95 OEM Service Release 2 (OSR2). An update to address this problem is now available, but is not fully regression-tested and should be applied only to computers experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft does not recommend implementing this update at this time.

This issue is resolved by the following updated file for Windows 95 OSR2:

   Esdi_506.pdr version 4.00.1116 (dated 8/25/97) and later
				

To install this update, follow these steps:

1.	Download the Remideup.exe file from the online service listed below to an empty folder.
2.	In My Computer or Windows Explorer, double-click the Remideup.exe file you downloaded in step 1.
3.	Follow the instructions on the screen.

The following file is available for download from the Microsoft Download Center:
For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.

The following files are installed by Remideup.exe:

   File name     Version    Date/Time       Size    Destination folder
   ------------------------------------------------------------------------
   Esdi_506.pdr  4.00.1116  8/25/97 11:16a  24,426  Windows\System\Iosubsys
   Voltrack.vxd  4.00.954   3/6/96 9:54a    18,518  Windows\System\Iosubsys
				

NOTE: The Voltrack.vxd file is installed on Windows 95 computers only. This file is not installed on computers running OSR2.

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Ultra DMA, also known as Ultra DMA/33, is an extension of the ATA hard disk interface that allows burst data transfer rates of 33.3 MB per second (double the ATA-2/ATA-3 standard of 16.6 MB per second).

This new standard is supported by controller chip sets such as the Intel PIIX4 chip set.

For additional information about issues resolved by updates to this component, please see the following articles in the Microsoft Knowledge Base:

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