DirectX installation error

Magicka started crashing on startup. While trying to fix this, I decided to update DirectX.
When I run dxwebsetup, it identifies missing "DirectX Runtime Optional Components" and attempts to install, but errors and tells me to check two log files.

Any help would be appreciated.

Error:

An internal system error occurred. Please refer to DXError.log and DirectX.log in your Windows folder to determine problem.

DirectX.log
Too long to paste here, on pastebin instead.

DXError.log:

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dxupdate(Nov 19 2010), file: dxupdate.cpp, line: 6497, function: CMDXCheck::IsAssemblyInUse

    GetAssemblyList() failed, error = 0x80070005.

--------------------
[12/28/11 13:24:59] module: dsetup32(Mar 30 2011), file: dxupdate.cpp, line: 280, function: CSetup::InstallPlugIn

    DirectXUpdateInstallPlugIn() failed.

First off, try the full DirectX 9 End-User Runtime Installer instead of the Web Updater.

Beyond that:

0x80070005 = "Access Denied".

Use something like Process Monitor to figure out what's it's trying to access (file, registry key, etc.) that's being denied; then examine that object to figure out why access is being denied.