CCleaner won't open in Windows

CCleaner for Windows CCleaner Windows Bug Reporting
1

I am unable to open CCleaner on my Windows PC. It was working fine when I last used it 2 days ago and I haven't installed anything since then so it doesn't appear that another program is interfering with it. When I click the icon, I get the standard Windows message asking if I'll allow the app to make changes and after clicking "Yes" nothing happens. I am using the Pro version.

2

Try Restarting the computer.

Note: not a shutdown/reboot - click "Restart".

3

Thanks for the suggestion. Unfortunately it didn't work but it's suddenly started working ok today!

4
9 minutes ago, revolver said: 
<div class="ipsQuote_contents ipsClearfix" data-gramm="false">
	<p>
		Thanks for the suggestion.  Unfortunately it didn't work but it's suddenly started working ok today!
	</p>
</div>

When CCleaner suddenly stops working and then just as suddenly starts again it's often because an antivirus definition starts to wrongly block it and then another AV definition update a day or two later corrects that block.

We see that happen most often when a new CCleaner version is released and the AV company takes a while to update their definitions for the new version. 

Some AV's are more prone to it than others.

As CCleaner Version 5.80 was released on Tuesday and you coudn't open it on Wednesday I suspect that is what happened here, ie your CCleaner updated and then your antivirus wouldn't let the new version run until the AV definitions got updated to recognise the new version.