BIOS versions 5.00 and higher are meant for use with Windows Vista only. Upgrade to BIOS versions higher than 5.00 only if Windows Vista is the operating system already installed on your computer, or if you are in the process of upgrading to Windows Vista.

BIOS versions 5.00 and higher are not compatible with Windows XP.

For the models listed above, if Windows XP is the installed operating system, and the computer's BIOS is upgraded to version 5.00 or higher, the Fn key combinations Fn+F1 though Fn+F9 may stop working.

Downgrade the BIOS to the newest version that supports the Windows XP operating system, from the Toshiba Service and Support website at http://pcsupport.toshiba.com. BIOSes that support Windows XP will have versions numbers lower than 5.00. BIOS versions 5.00 and higher are for Windows Vista only.

For further assistance, see also Support Bulletin 98081213 Obtaining downloads and support docs from the Toshiba Support website .

Use the table below to determine which XP-compatible BIOS is correct for your computer, depending upon the Part Number ("PART No.") on the large label on the underside of the computer. For each Part Number, the table shows the lowest BIOS version that it's possible to download to. Downgrade to this BIOS version, or to a newer BIOS with a higher version number, but be sure not to downgrade to another Vista-compatible BIOS (version 5.00, or higher).

After downloading a BIOS for your computer with a version number lower than 5.00, follow the installation instructions provided with the BIOS. You must use the diskette-based or CD-based method to downgrade the BIOS. The Windows-based method can not be used to downgrade the BIOS.

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