webpages error (no connection)

I have designed a layout which contains two regions, each only showing an HTML page. Unfortunately, the four HTML pages only change once or twice a day.

When I start the Xibo client, page refreshes work fine. But after some hours, the HTML pages won't be refreshed and the content is outdated. I turned off the cache in IE, but these settings seem to be ignored by the Xibo client. When I delete the cache files manually, the refresh immediately works again.

Is there a workaround for my problem? I read a lot in this launchpad, but couldn't manage it yet. Of course, I could schedule a service on the PC which from time to time deletes all cache files, but this seems to be hack, not a solution.

I'm using Xibo 1.5. on Windows 7 clients using IE 8

this problem come from the network ? or just add the script ?

note : i already put in html

<meta http-equiv="CACHE-CONTROL" content="NO-CACHE">
<meta http-equiv="PRAGMA" content="NO-CACHE">

I also inserted the following tags, and these worked:

<meta http-equiv="EXPIRES" content="0">
<meta http-equiv="refresh" content="30">

Thanks in advance,

Marlon Richard