maybe someone knows a solution for my voice problems, i try to exlain it short with my bad english

Voice generally works. We use P2P connection , but the problem is on both open voice chat and privat. The problem is that the voice from me is transfered normal and clear but the voice of the one i am talking to not. It sounds like it is overdriven , maybe like a robot. But the mic is just fine and it is not overdriven. Also the voice works fine without problems in morning and mid day hours it gets worse later on the day and on the evening hours. SL Time arround 2 PM - 6 PM. And it works 4 AM - .... I don't have a clue what the problem is because my voice is always clear doesn't matter wich time. So it normaly couldn't be a SL Serverside Problem?? But if its a Client side problem why does it work early on the day without changing anything on the clients pc? just boot it load sl and it works. boot it load sl on the later hours and it doesn't work. Sometimes it helps to reconnect the p2p call then the voice is clear for a moment sometimes for an hour sometimes just for some minutes and sometimes it wont change anything and the robot voice remains.