On a recent upgrade Microsoft also changed some network settings on Windows 7/10 pc’s that can cause problems with multi-user systems – Pegasus Software found this but it can affect Icaps as well:

Can you check the following registry keys have been added to any pc that accesses Icaps or Opera please.  This is to correct a setting MS decided would be a good idea to ignore the folder caching settings.  This does affect the way Windows handles the shares (incorrectly) on later versions of Windows.

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\LanmanWorkstation\Parameters]
“FileInfoCacheLifetime”=dword:00000000
“FileNotFoundCacheLifetime”=dword:00000000
“DirectoryCacheLifetime”=dword:00000000