"I wanted to change the default saving directory............so i followed these steps in the registry."
From what I've been reading on Google, doing that is a recipe for disaster and I'm not surprised you're having those problems.
Firstly, put things in the Registry back to how they were. In future when you're installing software, indicate that you want to install it on your W: drive. Not all programs give you a choice though.
Hopefully someone else will know a safe and reliable method to accomplish what you want.