Unable to retrieve thumbnails from vimeo

I just moved a drupal site from one (stage) host A to another (live) host B (different domain, different provider). After some routine tasks i stumbled upon a strange behaviour. It seems tebedded media field is no longer able to retrieve thumbnails from vimeo videos. Drupal watchdog tells "Could not connect to vimeo, HTTP error -110". I checked that it still works at my old host A so it can't be a vimeo api failure. I deleted cache at host B, ran cron and completely uninstalled emfield from my new drupal instance and reinstalled it - with no success. I tried Youtube thumbnails at the same field - they work (at host A and B). Weird.
Is there a setting from my old drupal instance A regarding emfield which needs to be removed? What else could i look into? I'm scratching my head now for hours, double checked settings without success.

I'm using Drupal 6.12 with emfield 1.2, i also tried emfield dev version.

Maybe someone has some ideas where i have to look into.

cheers, Ronald