Same problem here. I have the Parallels log set to debug and when it freezes the log fills up entirely with this, until I kill it:
09-14 18:28:34.280 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (676, 419, 0, 0, 0x0, abs)
09-14 18:28:34.296 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (676, 420, 0, 0, 0x0, abs)
09-14 18:28:34.320 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (676, 423, 0, 0, 0x0, abs)
09-14 18:28:34.360 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (676, 427, 0, 0, 0x0, abs)
09-14 18:28:34.392 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (676, 430, 0, 0, 0x0, abs)
09-14 18:28:34.400 Last message repeated 1 times.
09-14 18:28:34.456 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (676, 431, 0, 0, 0x0, abs)
09-14 18:28:35.305 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (1415, 817, 0, 0, 0x0, abs)
09-14 18:28:35.313 Last message repeated 1 times.
09-14 18:28:35.545 D /LocalDevices:13948:75023/ [CUsbMouse] Drop real_move, bogus event (1701, 793, 0, 0, 0x0, abs)