There was a fix for this some time ago. Illinois was having trouble updating.....try this.

For Win10
Right click the Start button > Settings > Apps   scroll down the list to ProSeries 2018, click Uninstall    It will act like its going to uninstall the whole program, don't panic, it wont!   Another window opens with a list of modules to uninstall, choose IL state.   

I believe for Win7, its under Control Panel > Add/Remove Programs  Uninstall PS18