Trojaner-Board - Offen .NET Framework 4 (x86 and x64) lässt sich nicht installieren

Hallo, ich wollte eine Software installieren und bekomme während der Installation folgende Meldung:

Component Microsoft .NET Framework 4 (x86 and x64) has failed to install with the following error message:
"A failure occurred attempting to install the .NET Framework 4 Full."

The following components failed to install:
- Microsoft .NET Framework 4 (x86 and x64)

See the setup log file located at 'C:\DOKUME~1\THOMAS~1\LOKALE~1\Temp\VSD261.tmp\install.log' for more information.

Inhalt der log file:
The following properties have been set:
Property: [AdminUser] = true {boolean}
Property: [InstallMode] = HomeSite {string}
Property: [ProcessorArchitecture] = Intel {string}
Property: [VersionNT] = 5.1.3 {version}
Running checks for package 'Windows Installer 3.1', phase BuildList
The following properties have been set for package 'Windows Installer 3.1':
Running checks for command 'WindowsInstaller3_1\WindowsInstaller-KB893803-v2-x86.exe'
Result of running operator 'VersionGreaterThanOrEqualTo' on property 'VersionMsi' and value '3.1': true
Result of checks for command 'WindowsInstaller3_1\WindowsInstaller-KB893803-v2-x86.exe' is 'Bypass'
'Windows Installer 3.1' RunCheck result: No Install Needed
Running checks for package 'Microsoft .NET Framework 4 (x86 and x64)', phase BuildList
Reading value 'Version' of registry key 'HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Full'
Unable to read registry value
Not setting value for property 'DotNet40Full_TargetVersion'
The following properties have been set for package 'Microsoft .NET Framework 4 (x86 and x64)':
Running checks for command 'DotNetFX40\dotNetFx40_Full_x86_x64.exe'
Result of running operator 'ValueEqualTo' on property 'InstallMode' and value 'HomeSite': true
Result of checks for command 'DotNetFX40\dotNetFx40_Full_x86_x64.exe' is 'Bypass'
Running checks for command 'DotNetFX40\dotNetFx40_Full_setup.exe'
Result of running operator 'ValueNotEqualTo' on property 'InstallMode' and value 'HomeSite': false
Skipping ByPassIf because Property 'DotNet40Full_TargetVersion' was not defined
Result of running operator 'ValueEqualTo' on property 'AdminUser' and value 'false': false
Result of running operator 'VersionLessThan' on property 'VersionNT' and value '5.1.2': false
Result of running operator 'ValueEqualTo' on property 'ProcessorArchitecture' and value 'IA64': false
Result of checks for command 'DotNetFX40\dotNetFx40_Full_setup.exe' is 'Install'
'Microsoft .NET Framework 4 (x86 and x64)' RunCheck result: Install Needed
Running checks for package '.NET Framework 3.5 SP1', phase BuildList
Reading value 'SP' of registry key 'HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.5'
Read integer value 1
Setting value '1 {int}' for property 'DotNet35SP'
The following properties have been set for package '.NET Framework 3.5 SP1':
Property: [DotNet35SP] = 1 {int}
Running checks for command 'DotNetFX35SP1\dotNetFx35setup.exe'
Result of running operator 'ValueGreaterThanEqualTo' on property 'DotNet35SP' and value '1': true
Result of checks for command 'DotNetFX35SP1\dotNetFx35setup.exe' is 'Bypass'
'.NET Framework 3.5 SP1' RunCheck result: No Install Needed
EULA for components 'Microsoft .NET Framework 4 (x86 and x64)' was accepted.
Copying files to temporary directory "C:\DOKUME~1\THOMAS~1\LOKALE~1\Temp\VSD261.tmp\"
Downloading files to "C:\DOKUME~1\THOMAS~1\LOKALE~1\Temp\VSD261.tmp\"
(05.04.2012 21:18:01) Downloading 'DotNetFX40\dotNetFx40_Full_setup.exe' from 'hxxp://go.microsoft.com/fwlink/?linkid=182805' to 'C:\DOKUME~1\THOMAS~1\LOKALE~1\Temp\VSD261.tmp\'
Download completed at 05.04.2012 21:18:07
Verifying file integrity of C:\DOKUME~1\THOMAS~1\LOKALE~1\Temp\VSD261.tmp\DotNetFX40\dotNetFx40_Full_setup.exe
WinVerifyTrust returned 0
File trusted
Running checks for package 'Microsoft .NET Framework 4 (x86 and x64)', phase BeforePackage
Reading value 'Version' of registry key 'HKLM\Software\Microsoft\NET Framework Setup\NDP\v4\Full'
Unable to read registry value
Not setting value for property 'DotNet40Full_TargetVersion'
The following properties have been set for package 'Microsoft .NET Framework 4 (x86 and x64)':
Running checks for command 'DotNetFX40\dotNetFx40_Full_setup.exe'
Result of running operator 'ValueNotEqualTo' on property 'InstallMode' and value 'HomeSite': false
Skipping ByPassIf because Property 'DotNet40Full_TargetVersion' was not defined
Result of running operator 'ValueEqualTo' on property 'AdminUser' and value 'false': false
Result of running operator 'VersionLessThan' on property 'VersionNT' and value '5.1.2': false
Result of running operator 'ValueEqualTo' on property 'ProcessorArchitecture' and value 'IA64': false
Result of checks for command 'DotNetFX40\dotNetFx40_Full_setup.exe' is 'Install'
'Microsoft .NET Framework 4 (x86 and x64)' RunCheck result: Install Needed
Verifying file integrity of C:\DOKUME~1\THOMAS~1\LOKALE~1\Temp\VSD261.tmp\DotNetFX40\dotNetFx40_Full_setup.exe
WinVerifyTrust returned 0
File trusted
Installing using command 'C:\DOKUME~1\THOMAS~1\LOKALE~1\Temp\VSD261.tmp\DotNetFX40\dotNetFx40_Full_setup.exe' and parameters ' /q /norestart /ChainingPackage FullX64Bootstrapper /lcid 1033'
Process exited with code -1073741819
Status of package 'Microsoft .NET Framework 4 (x86 and x64)' after install is 'InstallFailed'

Bin echt ratlos, vieleicht kann mir hier jemand helfen.