Your example gives me identical results no matter what case I use – I think you just managed to hit different data servers with your two queries, which explains the slightly different results.

Yes, could be. But then, what triggers this? I could repeat the behaviour the whole day through.

And also...

'auto' search in six different languages yield different results and also different sensitivies to case.

google.com (case insensitive)
google.fr (case sensitive)
google.de (case sensitive)
google.com.tr (case insensitive)
google.be (case sensitive)
google.ro (case insensitive)