Windows Explorer hangs trying to show computer resources

Hello all
Windows Explorer no longer shows computer resources on my Windows 7. When I open "Computer" the green bar keeps growing very slowly and no content is shown. I've already tried to clean all temporary files and reboot many times. There are many issues on Google about this but I couldn't find anything useful for me.
Further, it sometimes happens that when I open a single folder I can see its content but the other (sub)folders are not shown on the left tree.

(see example here)

Can anyone give a good tip to figure out the problem?

Thank you for replying Andrew
I run SFC /scannow and it reported that some corrupted files were found and restored. But:
1. The problems with Explorer have not been solved
2. I tried to restart the PC and run SFC /SCANNOW 2 other times and everytime it ended with same result (some corrupted file found and restored) but anything has been fixex, actually.

Futhermore, Explorer is becoming more and more unresponsive: I can clic on single folder(s) and see the content, but cliclick on the "computer" icon always takes it to hang on an endless green bar and no content is shown; also, clicking on a folder on the folder tree often doesn't open the tree, only show the content of the selected folder.

In short, I can reach every folder (except than "computer") but I have to write its path directly while browsing is becoming practically impossible.
The issues are not user dependant, no matter which user is logged, all are affected, included the administrator(s).

Looks like Windows is too much corrupted somewhere and that the only solution is reinstalling everything. Since the number of programs installed this would be my very last choice, but I've already tried everything

Hello again and sorry for the late reply.
I tried to make a repair install as described on the link provided, but problem are still there, nothing is changed
And I honestly surprised of this. Anyway, since nothing tried has did the trick I'm going to make a clean reinstall of Windows. Thanks for your support.