array_flip() [function.array-flip]: Can only flip STRING and INTEGER values! in DrupalDefaultEntityController->load() (line 177)

Getting this error on a frontpage made with panels and views, including multiple filefields (both hidden and viewable).

Warning: array_flip() [function.array-flip]: Can only flip STRING and INTEGER values! in DrupalDefaultEntityController->load() (line 177 of /home/www/new.medmesh.org/includes/entity.inc).

When I hide the panel view containting above the error does not show. However after reading something about cache settings I activated the view's cache and the message disappear.

It applies also to the 7.x.beta3 version, and "upgrade" to dev (27 april) did not have immidiate effect.

I also had suspicious towards token module and pathauto because it appeared after theses where activaded, but even without theses modules the error persisted.

Line 177 in entity.inc referrres to this code and text:
// Create a new variable which is either a prepared version of the $ids
// array for later comparison with the entity cache, or FALSE if no $ids
// were passed. The $ids array is reduced as items are loaded from cache,
// and we need to know if it's empty for this reason to avoid querying the
// database when all requested entities are loaded from cache.
Line 177--> $passed_ids = !empty($ids) ? array_flip($ids) : FALSE;
// Try to load entities from the static cache, if the entity type supports
// static caching.

My conclution is that something is faulty in the way views handles/showing the view in a non-cached mode in conbination with multiple fields (hidden ones)! Hope the community can look into this in a more qualified way that I can.

Thanks