OWSTIMER keeps old copy of an assembly so new Feature Reciver code not picked up on deploy

When you install/uninstall a Feature that has a FeatureReceiver OWSTIMER keeps a handle open on the dll containing the feature receiver until its restared

This means that when you uninstall the feature Fusion will move the dll to the c:\windows\temp\ directory and still keep the reference.

When you then try and install the new version, OWSTIMER will run the OLD feature receiver, meaning that your new code, the stuff you've just installed, doesn't fire.

You can stop this occurring with a restart of the OWSTIMER service «SharePoint 2010 Timer», and now the OWSTIMER will run the new feature receiver.