Q IÆm trying to reinstall Win 95 on my PC, but IÆm experiencing a problem with my hard drive. Apparently Windows is using MS-DOS compatibility mode for both 540MB drives. I checked the help and it said to remove all my config.sys device drivers that are used by MS-DOS applications. But these are the only statements in my config.sys:

A If your hard drives are operating in "MS-DOS Compatibility Mode", then Windows 95Æs 32-bit protected-mode disk drivers have failed to load and your system is resorting to 16-bit real-mode crutches.

To discover the status of your system, open the System Control Panel and select the Performance tab. The message "Your system is configured for optimal performance" indicates that all is well, while a notice to the effect that "Compatibility Mode Paging reduces overall system performance" tells you that at least one of your hard drives is acting up. (Note: the message "Some drives are using MS-DOS compatibility" indicates a problem with your floppy or CD-ROM drives).

Your first troubleshooting step should be to run your (up-to-date) virus scanner against all your hard drives. A master boot record virus can trick Windows into displaying all kinds of error messages, none of which will reveal the true cause of the problem.

If your system is clean, use the information on the Performance tab to help you determine how to proceed. If youÆre "lucky", Windows will name an offending driver. A reference to mbrint13.sys could indicate that your hard drive is incompatible with Windows 95Æs 32-bit disk drivers. This can most likely be fixed by using the correct geometry translation software (see support.microsoft.com/support/kb/articles/Q126/8/55.asp for an extensive discussion of Win 95Æs support of large IDE drives.) If the Performance tab references a driver in your config.sys file, this may be preventing Windows 95 from loading its protected-mode drivers. In this case, your drive vendorÆs Web site is the place to go for workarounds or updates.

If Windows doesnÆt pinpoint a particular driver, click on Hard disk controllers on the Device Manager tab of the System Properties dialogue box. A yellow exclamation mark indicates a probable address or IRQ conflict. With the controller name highlighted, click Properties and select the Resources tab. If a resource conflict is listed in the lower section of this dialogue box, reconfigure the settings for the disk controller or for the conflicting device and then restart Windows.

If the problem persists, the protected-mode disk driver may have been corrupted. Extract the appropriate driver file for your hard drive (esdi_506.pdr for IDE drives, scsiport.pdr for SCSI drivers) from the Win 95 installation CD or disks. (If youÆre not sure how to do this, see Replacing corrupted files, May 97, p148). Copy the extracted file to \Windows\system\iosubsys.