sorry for the question above, I doesn't belong here:
I found the cause by myself, and I am posting my own reply in case somebody else has the same problem.
It is windows 7 that is causing this trouble.
Microsoft is actually distorting the text information because they think this makes the text better readable, but ignoring the customers that have problems with it because it is not so easy to disable this "feature".
Here is a link I found that gives a possible solution: