Stats start showing "no data"

Sometimes the stats just show no data. I mean like I am looking at a page one minute, refresh and then no data to display.

The data wont come back either.

Why does this happen?

In fact, I had a whole custom dashboard working, showing custom variable stats (it was a custom dashboard as a php page with manual iframe inclusions, not within the piwik admin but in another site) and then no data showing at all.

When i check one of the iframes in another browser i get “The requested website idSite is not found in the request, or is invalid. Please check that you are logged in Piwik and have permission to access the specified website.”

The Siteid obvisouly exists as it was showing data 2 mins ago.

url being used is:;customVariablePageValue2==Memberid_536

Also, this happen around midnight. Could it be a date based error? Log file issue?

The 30 days evolution widget (visit summary) still shows ok however. The other 8 or so show no data.