I hope this may help other users who experience similar issues. One of our servers was updated in IW RC channel, but upon checking using Internet Explorer (11), from 3 different computers, the control panel was not working as expected.
Kudos to IW-Jenna for helping/looking at the issue, and suggesting try in private browsing, which worked lovely.
This would indicate an issue on the computers, and not with themes/control panel of IW, so I did a little research, and below I found an answer which appears to work lovely. It is from microsoft and I have included the full link to the answer.
I hope it does help others
run the following code in command box with Administrator rights
icacls %userprofile%\Appdata\LocalLow /t /setintegritylevel (OI)(CI)L
Many thanks