The last few lines of the log show:
<Func Name='LaunchFunction'>
Function=Write_sqlRegSDDL
<Func Name='SetCAContext'>
<EndFunc Name='SetCAContext' Return='T' GetLastError='203'>
Doing Action: Write_sqlRegSDDL
PerfTime Start: Write_sqlRegSDDL : Tue Nov 08 23:13:03 2005
WinXP Pro SP2, just FDISK'd and re-installed my OS today - no leftover RC/CTP bits on the machine.
I'm logged in with my Domain account. I belong to the local Administrators group and am able to install other software (also installed all of the client tools such as SQL Server Management Studio, etc.

SQL Express hangs on "Setting Registry Security"
AmitJoshi
eric_delage
I am getting the same problem.
I aborted, cleaned up the failed install a number of times. But kept getting the same problem at the same place.
Finally I let the install run all night and it appears to have worked.
You need to leave the machine alone for at least 2 hours.
I am not sure what makes my PC suseptible to this error.
jimmyglo