First, why not solve the initial problem instead?
90% of the times, the problem that you are facing (when changing orientation) is solved in this question:
Background task, progress dialog, orientation change - is there any 100% working solution?
Read it, correct your code and see if the problems are gone!
If you still want to do it anyway:
Quoting the documentation:
Note: Handling the configuration
change yourself can make it much more
difficult to use alternative
resources, because the system does not
automatically apply them for you. This
technique should be considered a last
resort and is not recommended for most
applications.
Still want to do it? Read the following link (where I also found the quotation):
http://developer.android.com/guide/topics/resources/runtime-changes.html#HandlingTheChange
If you rely on android system to use different layouts when you are on portrait/landscape mode, you'll need to start to handle these differences by yourself. If you don't use these features, you may get away without doing nothing fancy :)