Installation problem - "catastrophic failure"

Hi,

I've having major troubles installing IIS -

The 1st error in the log (iis6.log in c:\windows\) I see is:

[12/3/2007 11:48:34] OC_COMPLETE_INSTALLATION:iis_core:MyMessageBox:
Title:IIS Setup Error, Msg:Error calling procedure 'DllRegisterServer()' in
file 'C:\WINDOWS\system32\inetsrv\iislog.dll'. 0x8000ffff=Catastrophic
failure

Followed by a bunch of
[12/3/2007 11:48:34] OC_COMPLETE_INSTALLATION:iis_core:MyMessageBox:
Title:IIS Setup Error, Msg:Error Setting IIS Metabase data.
0x80070005=Access is denied.

The machine is WIN XP SP2,
I'm running as a local administrator.

I've tried a few things -
uninstalling / reinstalling (with reboots)
Making sure system32\inetsrv really has gone
Deleting the rsa machine keys used by iis and re-installing
checking the registry to make sure the rsa key has the correct machine guid
turning off virus scanners

but I keep getting the same problem.

Does anyone have any other suggestions of what to try. I really don't want
to clean the machine and start again!!!

Thanks,

Graeme