Windows is good depending on who its for and drives other absolutely insane, like me, unfortunately, there are good things that come with a catch
Well as to the problem, best idea is always to have a clean desktop, whenever I don't have use for desktop items immediately or are no longer needed I other shove them in a folder labelled 'desktop' which is acessable from the task bar or delete them.
As for freeing up the gigabites, I managed to free up loads recently by disk cleanup (estimated 16gb but did 12) try using disk clean up, not to be patronising, but some people can never find disk clean up, check your HD properties from My Computer
And perhaps theres a lot of wasted space there.
As for the restarting issues, not a clue, my sister had that problem, I think it sorted out when we had to take it to the shop, or I think it stopped after a while, it was a lil while back so useless info like that doesn't stay in
I am sparticus and so is my wife