I'm having problems installing the .Net Framework 4.0 Runtime on a Windows Vista machine. When I try to run the installer (I tried both the Web installer and the offline version) nothing happens. By taking a look at Task Manager a corresponding process keeps running indefinitely but no noticeable CPU activity ocurrs. I get no splash screen, no eula, no error popups. If the UAC is enabled the elevation popup takes place, though. I tried the usual steps: disabbling the UAC, disabbling and even removing the Anti-Virus. Also the where no noticeable events in Windows Events.
As an additional measure I ran the Windows Update (the pc was on Service Pack 1) and applied all the pending updates (including Service Pack 2) to no avail.