At least it's not a general problem, which likely means that the settings in your client aren't correct. Have you read through and followed the steps in our PokerStars FAQ? It can be found here: I'm having problems at PokerStars, what can I do?
PS also works with me not, have done everything from FAQ, to the advanced settings, it will not save the new path to my hand history folder, what can I do?
I think you should try to delete all the Pokerstars client first, and then install it again in english language.
And not changing the language directly on the client when you are logged on.