.Net 4 in Win7 x64 Ent Task Sequence???

[Nik]

Can anyone give me some advice on where I am going wrong with my .Net
Framework v4 installer, it launches, then hangs without reponse for over an
hour, as soon as i terminate the dotNetFx40_Full_x86_x64.exe process the task
sequence passes through, without the installation completing. The temporary
folder created is still there with full contents...

I've pasted the command line and log file below... and yes I have
googled/binged the error code "Error 0x80070424: Failed to open the current
cluster" but only seem to find errors re: installation of .Net RC or Beta on
MAC hardware, or Boot camped machines. I am trying to create a Win7 x64
reference build on a Dell E6400, with nothing else on the drive.

Previous steps are O/S and Windows update. Any ideas?

Command Line:
dotNetFx40_Full_x86_x64.exe /q /norestart /log %temp%\dotNetFx40.log

Log File:
[5/14/2010, 15:55:13] === Logging started: 2010/05/14 15:55:13 ===
[5/14/2010, 15:55:13] Executable:
\\BUILD-SRV01\x64\Applications\Microsoft_dotNetFx40_Full_x86_x64\dotNetFx40_Full_x86_x64.exe v4.0.30319.1
[5/14/2010, 15:55:13] --- logging level: standard ---
[5/14/2010, 15:55:13] Successfully bound to the ClusApi.dll
[5/14/2010, 15:55:13] Error 0x80070424: Failed to open the current cluster
[5/14/2010, 15:55:13] Cluster drive map: ''
[5/14/2010, 15:55:13] Considering drive: 'C:\'...
[5/14/2010, 15:55:13] Considering drive: 'D:\'...
[5/14/2010, 15:55:13] Drive 'D:\' is rejected because of the unknown or
unsuitable drive type
[5/14/2010, 15:55:13] Considering drive: 'E:\'...
[5/14/2010, 15:55:13] Considering drive: 'Z:\'...
[5/14/2010, 15:55:13] Drive 'Z:\' is rejected because of the unknown or
unsuitable drive type
[5/14/2010, 15:55:13] Drive 'C:\' has been selected as the largest fixed drive
[5/14/2010, 15:55:13] Directory 'C:\0f067220b1472c9377e56332d18a12fd\' has
been selected for file extraction
[5/14/2010, 15:55:13] Extracting files to:
C:\0f067220b1472c9377e56332d18a12fd\