Once you open PC Cleaner on your computer and you decided to X it out It stays on your system tray as open. So when you launch it again using the desktop Icon it will just do nothing , because it is already open under the system tray. You just need to click the system tray icon once or double click then click the PC icon and it will launch without problems.
The system tray is located in the Windows taskbar (usually at the bottom next to the clock) and contains miniature icons for easy access to system functions such as fax, printer, modem, volume, and more. Double click or right click on an icon to view and access the details and controls.