This article was previously published under Q139987
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After you upgrade an Acer computer from an earlier version of Windows toWindows 95, the following problems may occur:
The CD-ROM drive is not detected.
32-bit disk and file access is not available.
These symptoms may also occur when you upgrade an Acer 91.AA260 computerto Windows 98.
These problems can occur if the CD-ROM drive is connected to a CMD CSA-6400E PCI IDE controller. The Cmd640x.sys real-mode driver on Acercomputers is designed to work in Windows 3.1 and does not work inWindows 95.
If you use the CMD 6400 PCI controller protected-mode driver CMD CSA-6400E, 32-bit disk and file access is functional but the CD-ROM drive isnot detected.
If you use the CMD 6400 PCI controller real-mode driver Cmd640x.sys, theCD-ROM drive is detected, but 32-bit disk and file access is notavailable.
All Acer computer systems with a part number starting with 91.AA043 or91.AA260 using the CMD CSA-6400E PCI IDE controller and a Maxtor 7546AThard disk running Windows 95 exhibit this behavior.
To correct this problem, load the Windows 95 version of the CMD CSA-6400E PCI IDE driver. Download the self-extracting file Cmdwin95.exefrom Acer's FTP server (ftp.acer.com), or from Acer's World Wide Website (www.acer.com/aac/win95/upgrades/ftp.htm). For additionalinformation, please contact Acer Technical Support.
You may be able to resolve this issue using the following steps:
Click Start, point to Settings, and then click Control Panel.
Double-click System, and then click the Device Manager tab.
Double-click Hard Disk Controllers, and then double-click CMD 640 Bus Master Controller.
On the Settings tab, click Both IDE Channels Enabled in the Dual IDE Channel Settings box, click OK, and then click OK.