i just noticed that there is an error when scrolling in Adobe Reader with any Logitech mouse which has microgear. For those who dont know that: it allows very fast scrolling and the "click" while scrolling with the weel is turned off.
So when i scroll very fast through any document, the direction reverses sometimes. So if i scroll down, for a few seconds while scrolling downwards the document scrolls up again. I tried this with and without drivers and on many computers. In all other programs it works perfectly. in addition i got two mice with this technology, one is brand new and its the same with both.