Slow movement due to CPU

I opened the task manager , then Processes tab , I found explorer.exe has about 40 in CPU , the others are normal - i think - So I ended this process but the icons on desktop disappeared and the lower bar also disappeared.

P.s: I already removed IE and using Chrome.

So What was explorer.exe ? and what's the solution to the slow movement ?

After I ended the explorer.exe still the problem exists ..