Turn off all startup files Via msconfig, or CCleaner. Restart. See if the problem corrects itself. If it does then add back in only those that you, personally, know you would need to start anyway.
If no help then run sfc /scannow see if that corrects it.
Hmmm, good question. Do you mean Windows explorer, ie. your desktop, or Windows Internet Explorer, ie. your browser? They are two different things and often confused.