I haven't been able to figure out what triggers it, but once in a while my Babyface drivers are unable to control the buffer size. As an example, I'll have my DAW open and I'll bring up the USB settings to change the buffer from the dropdown menu, but although the control panel shows the new value, the DAW doesn't. The audio stream is never interrupted and the buffer size stays the same.

If I close the DAW and reopen it, it will show the new buffer size, however it's now de-synchronized and plays back at the wrong rate (faster or slower, depending on whether the buffer was increased or decreased relative to the old size). If I change the sample rate after changing the buffer size, the new buffer size is applied correctly. If I log out of Windows and back in, the problem disappears and everything is normal again.

Is this a known issue, or does it sound like there's an obvious solution?

(System: i7 920, W7 x64, latest firmware, tried latest stable drivers and beta drivers.)