Windows 7, Explorer wont refresh automatically

hi there,
i've noticed this problem, started a couple of days ago, out of the blue.
i cant remember tweaking anything and getting this.
windows explorer wont refresh the files automatically after an operation is done.
here are some examples:
i copy a file from one folder to another, i get the copy box and when that finishes nothing happens, i have to manually use f5 on both folders to see the new file's location.
if i try to create a new folder on the desktop, or unzip a folder to my desktop, it wont become visible until i pres f5.
i delete a bunch of files and they remain there, they will only disappear when i push f5...

any ideas why this is happening? any clues, where should i look into?
(using windows 7)

thank you