Already tried that....
- extracted the mp10setup.exe
- repacked it with IExpress - using:
[code]SETUP_WM.EXE /Q /R:N /NoPID /DisallowSystemRestore/[code]
- and placed the resulting file in SVC-PRE [runs before hotfixes]
I turned off System Restore on the test machine I'm using and tried it out - works fine - no requesters or anything.
I still got the same error during the UA XP CD install however

I'm thinking it must be a hotfix thats being run after the Media player 10 is installed - that does the same popup requester.
All the media player 10 hotfixes documented in the thread
http://www.msfn.org/board/index.php?showtopic=31886 seem to be the normal ones so its gonna be tough to work out.
I've said no to the requester and let the install continue to see what hotfix is left at the end.
Cant think off the top of my head how to check a "log" of what happens during the install of xp - surely it would mention the "cancel"ing of the requester I'd have thought in the log.
I should know this answer and this is seriously wasting my time at work but what is the tool i can run on the machine to find out whats missing - or is there some way i can find out the troublesome hotfix?
Update:It looks to be the old 891122 hotfix according to the KBxxxxxx txt files

I'll try a build without that one and see what happens
update2:It installed lovely now - just need to install the lan drivers to see what Windows Update reports

Cheers
Nath