Recently put a clean install of Windows 7 x64 on a laptop. Now all imaging-related apps seem to hang on close, approx. one time out of every 10 runs.
I close an imaging app (Photoshop CS5 x64, Photoshop CS5 x32, or Irfanview 4.30). Approximately one out of ten times, the app window will close, but the process will remain running, visible in the Processes tab of the Task Manager.
These processes use minimal CPU ( < 1% ) and does not interfere with future instances of the application (Photoshop or Irfanview can be opened again while the hung process is present).
This does not happen with any other apps than those mentioned above.
For Irfanview, this will happen 100% of the time if the Save for Web plugin is used, and then the program is closed via the Esc key.
Found a related topic here, although no solution was found.
This behavior does not appear on Windows XP. Tested with clean installs of Windows 7 x64 SP1 Ultimate, Windows XP SP3 Pro and Windows XP 64-bit SP2.