On the Microsoft Windows platform iCall uses the Internet Explorer software as it's core interface.
This specific problem is caused by altering your web page caching settings in Internet Explorer to never cache any data.
To fix this problem follow these steps:
1) Exit iCall completely.
2) Open Internet Explorer.
3) In Internet Explorer choose "Tools" and then choose "Internet Options"
4) Under the section that now says "Temporary Internet Files" select the button that says "Settings".
5) Choose the radio button next to the word "Automatically". Click "OK".
6) Start iCall and the problem should be resolved.