For example, you may have some .Net 1.1.4 COM+ serviced components running under dllhost.exe, and not be able to re-compile them using .net 2.0 for some reasons. You can forcefully run them under .Net 2.0 framework.
You just need to create a dllhost.exe.config file for the %windir%\system32\dllhost.exe. Please note the filename has to be dllhost.exe.config and be placed along with your dllhost.exe. You need this .config file to specify the runtime version you want.
dllhost.exe.config:
<?xml version ="1.0"?>
<configuration>
<startup>
<requiredRuntime version="v2.0.50727" safemode="true"/>
<supportedRuntime version="v2.0.50727" safemode="true"/>
</startup>
</configuration>