Hi,
From your post I see that you are getting the following error “a previous instance is already running" from Dell support Centre.
When exactly do you get the error?
On my research I have found out that uninstalling and re-installing Dell Support Center on the computer has helped people solving the issue.
Dell Support center download link:
http://www.dell.com/content/topics/global.aspx/services/en/dsc_home?c=us&l=en&s=gen
You may refer this Dell discussion:
http://en.community.dell.com/support-forums/software-os/f/3526/p/19379827/19876568.aspx
You may want to contact Dell community for further help:
http://en.community.dell.com/?~ck=mn
Hope it helps!
Let us know if you need any assistance on Windows.