Hi,
Some possibilities to check:
Are there other pull up resistors on the SDA and SCL lines for other devices? These would be in parallel with the 2.2k resistors and may make the total parallel resistance too small. For 3.3V the Rpmin is about 1k.
Is there a random spike on the SCL line that is not showing up on the oscilloscope? This would be interpreted by the device as another clock pulse.
Mike