Testplatform HP Pavilion DV-5 Entertainment Notebook PC (4GB RAM, 2GHz dual-core) with MicrosoftÃ‚Â® WindowsÃ‚Â® 7 7048 x64 and Creative Sound Blaster X-Fi Surround 5.1. Driver: USB_W7DRVBETA_US_1_01_0091.exe. Tested with clean installed OS and only this driver. The Sound Blaster X-Fi Surround 5.1 is connected with optical TOSlink to a 5.1 Pioneer reciever. There occures great (and increasing) latency while playback of videofiles. -Sound will very noticably loose sync from video within a minute (all filetypes, not a codec problem). The latency will not occure with the internal notebook speakers, nor on same system with MicrosoftÃ‚Â® WindowsÃ‚Â® Vista x86. The Notebook ships with HPs "AMD USB Filter Driver" that should improve the performance of USB accessories, such as USB speakers or a USB TV tuner. I have tried to install this also on the testplatform to resolve the problem, however even though it seems to install fine the latency/syncproblem still resists. Any ideas?