不曉得您有沒有看過官方網站上的相關說明呢?
引用關於 WinXP 的部份如下:
Windows 2000/XP: DVD Region Killer 2 will not work on Windows 2000/XP with DVD Player software which uses an ASPI Layer. If your player software does use an ASPI Layer, you should update it, e.g. the newest versions of Cinemaster, ELSA, ATI or PowerDVD do not use ASPI under Windows 2000/XP.

另外版本演進內也有說明支援的 OS:
Version 2.3.0.1, December 8, 2001
Improved ElbyCheck: The scan for corrupt filter drivers will only be started, if no CD-ROMs are present. (Windows 2000/XP)
Improved Install / Deinstall of Filter driver, fixing various compatibility problems. (Windows 2000/XP)

Version 2.2.0.1, December 3, 2001
Improved region code automatic on Windows 2000/XP
Improved DVD-ROM detection on Windows 2000/XP
Improved Filter installation/deletion on Windows 2000/XP
Changing Autostart didn't work, if you weren't Administrator on Windows 2000/XP
Added "ElbyCheck" program, which will monitor the installed filters of CD-ROMs/DVD-ROMs
Some Games like FIFA2002 didn't work, if Region Killer 2.1.0.1 was installed on Windows 95/98/ME


給您參考一下~

Re: WinDVD vs Windows XP 的區碼問題！
 

我也有過windows的區碼從兩次變一次，不過還是不影響Genie功能，不過我是用2000就是了！

我之前也有遇過這個問題，後來我的方法是
重新安裝WinDVD，但是先不要升級成3.1版
然後用DVD Genie 去勾選
強迫使用WinDVD的內部區碼
之後才去升級WinDVD，這樣子用WinDVD就不會被WinXp的區碼給鎖住了

WinXP在偵測到DVD片時會跳出一個視窗，
如果你選擇用MediaPlayer播DVD，OS就會去作區碼偵測。
我個人的感覺是~用PowerDVD或WinDVD的面板來播就好啦!
MediaPlayer也沒有比較好...:)