There's probably something interfering. I would bet my bucks on a virus or other malware, or something related, perhaps a linked program you've downloaded. An ever increasing problem is attachments that come automatically when you download and install something.
Two easy ways to check it:
1. Pick a Restore Point at Control Panel\All Control Panel Items\Recovery > Open System Recovery. After clicking "Next" you'll see options, plus tick box "Show more restore points". Take one earlier than your problems started.
2. Take a look at what you have installed in the past few days, in Control Panel\Programs\Programs and Features, or via Revo Uninstaller, uninstall whatever you may suspect = everything new.
Plus: in any case you should hunt down any possible threats = do a thorough scan with your Antivirus and, say, Malwarebyte.
Must ask: it is Explorer.exe, not Explore.exe which is known as a vicious one? Although the latter may be obsolete by now.