A Windows 98/Me computer with a Peripheral Component Interconnect (PCI)
Integrated Drive Electronics (IDE) hard disk controller using serialization
between the two IDE channels can take a big performance hit if the OS cannot
initialize the protected mode drivers. When this happens, the hard disk will run
in MS-DOS Compatibility Mode, which means it’s using 16-bit, or real mode,
drivers for both the file system and the virtual memory. To help you combat this
issue, I’ll explain some troubleshooting steps to correct MS-DOS Compatibility
Mode problems in Windows 98 and Windows Me.The problem in more detail
While the MS-DOS Compatibility Mode problem may appear to be caused by some sort of bug in the operating system, it’s actually the result of an automatically implemented workaround that allows Windows to continue to operate even though it can’t load the protected mode driver. More specifically, when Windows 98/Me isn't able to properly initialize the protected mode driver for the IDE controller in the system, the operating system automatically loads a default real-mode driver and then places a value in the registry called NOIDE. This value will prevent the operating system from attempting to load the protected-mode driver, thus permanently dooming the system to using real-mode drivers for both the file system and the virtual memory.
If you happened to miss, or misunderstand, the original error message, you might not know that the system is using real-mode drivers for both the file system and virtual memory. Once you begin your troubleshooting investigation into the cause of the system’s poor performance, however, you'd encounter a Performance tab in the System Properties sheet like the one shown in Figure A. (To get to the System Properties sheet, right-click My Computer and select Properties.)
| Figure A |
 |
| When the operating system runs in MS-DOS Compatibility Mode, it’s managing the hard disk and the CD-ROM with real-mode drivers, and performance will be degraded. |
The information on this tab indicates that on this particular computer, the operating system is using MS-DOS Compatibility Mode for both the hard disk and the CD-ROM drive. If you investigated Device Manager on this computer, you’d see that both the primary and secondary IDE channels show an exclamation point (!) in a yellow circle underneath the Hard Disk Controllers category, as shown in Figure B.
| Figure B |
 |
| Device Manager indicates a problem with the primary and secondary IDE controllers. |
Attempt to reload the driver
As long as the NOIDE value is in the registry, the operating system will not attempt to load the protected-mode driver. So the first thing to do is to get the operating system to reload the protected-mode driver. You'll need to take this approach because the minor hiccup that occurred while the system was trying to load the driver could have caused the initial failure. It’s best to test this theory first. To do so, you must remove the NOIDE value from the registry.
Warning
Working with the registry could affect other parts of the operating system. Use extreme caution when making changes to the registry.
To begin, select Run from the Start menu and launch the Registry Editor by typing Regedit.exe in the Open text box in the Run dialog box. Once you have the Registry Editor up and running, locate and double-click on the key HKEY_LOCAL_MACHINE. When this subtree is visible, open each of the following subtrees in succession:
- System
- CurrentControlSet
- Services
- VxD
- IOS
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Thank you very much for your help with this problem. I followed your directions and they solved my problem on the first try.Thanks again
Don
Posted by DON HUMPHREY on Thursday, March 06 2003 11:51 AM