Need more info on your system. Make and model, Operating system used, RAM installed and so forth.
There are literally millions of people using Lightroom without any problems what so ever, me being one of them. So the problems you are having boils down to your computer in one way or another.
If you use Lightroom only occasionally, you said you were Done with Lightroom, I suggest you don't bother with it and use Bridge and Adobe Camera Raw instead.
Lightroom is not a program you use for only one project. It is an Image Cataloging and non destructive editing program. It uses a Database system to catalog all images you import to it.
Once Lightroom is installed you shouldn't be getting any Download Error as it isn't downloading anything from the net.
A supercilious and unhelpful reply really. If you have no knowledge of anyone having a problem with Lightroom then you should not try to respond to a user who does. I use LR continuously for professional photog projects. The fact of finishing one project does not preclude another. The problem actually began when starting the "rented" Photographer's Package version via the Cloud and the problem seems to be with the Cloud. The Literal Millions may use LR seamlessly but that does not help the Virtual Thousands of us who do not.
I have PS CC 2014 installed on my system along with Lightroom stand alone version. Neither program is dependent on the Clouds. They are fully downloaded and installed to the local computer. Yes they may check licensing over the net but that is something very different from running on, being dependent on, a cloud based system. Every version of PS for years and LR, along with many other programs, do that same license checking over the internet.
You didn't bother answering the questions I asked.
A supercilious and unhelpful reply really. If you have no knowledge of anyone having a problem with Lightroom then you should not try to respond to a user who does. I use LR continuously for professional photog projects
...All of which posturing is utterly irrelevant to the request for more information, and - frankly - not likely to impress anyone here. Your smugly self-proclaimed credentials are no substitute for telling us what the problem is...
You haven't even told us which OS or which Lightroom version - either of which details might well be entirely relevant, and which - let's be clear - you don't know aren't relevant.
So. Wanna try again with a bit less attitude?
No. Thank you.