Dear Gareth,
Thank you for using the Newsgroups.
For the issue you mentioned, we recommend you to post in following TechNet
Forum in order to get the most qualified support deliver, and other
partners who read the forum regularly can either share their knowledge or
learn from your interaction with us.
Windows XP Service Pack 3 Feedback Forum on Microsoft TechNet
http://forums.microsoft.com/TechNet/ShowForum.aspx?ForumID=2010&SiteID=17
By the way, I'd like to share some of my experiences for your reference.
You may try following steps to check if the computer can boot.
Solution 1:
========
1.Press F8 when you reboot your computer.
2.Select "Last Known Good Configuration (your most recent settings that
worked)"
3.Select "Windows XP Professional"
Solution 2:
========
You may try to uninstall Windows XP SP3 RC0 Beta based on the following KB.
How to remove Windows XP Service Pack 2 from your computer
http://support.microsoft.com/kb/875350
This KB is completely works on Windows XP Service Pack 2 and it should be
works on Windows XP Service Pack 3 RC1
Solution 3:
========
You may perform an in-place upgrade to repair this computer. For detailed
steps, please refer to Method 2 in the following KB article:
315341 How to perform an in-place upgrade (reinstallation) of Windows XP
http://support.microsoft.com/default.aspx?scid=kb;EN-US;315341
This method will replace the system files to the original versions.
Therefore, if the system can boot correct after the in-place upgrade,
please apply Windows XP SP2 and other updates.
I hope any solution above can help you, If all the solution doesn't work,
please post in following TechNet Forum in order to get the most qualified
support deliver.
Windows XP Service Pack 3 Feedback Forum on Microsoft TechNet
http://forums.microsoft.com/TechNet/ShowForum.aspx?ForumID=2010&SiteID=17
Thank you for your understanding.
Thanks & Regards,
David Shen
Microsoft Online Partner Support
Microsoft Global Technology Support Center