If you have a large number of extensions installed then disabling them one by one may take a significant length of time. Disable one half of your extensions to see if the problem still exists:
If it does, then you know the problem exists in the second half, so you disable half of the remaining enabled extensions, and test again.
If it doesn't, then you know the problem exists in the first half, so you re-enable half of the extensions we just disabled and test again.
By recursively enabling or disabling extensions in this manner you can home in on a misbehaving extension quicker than disabling them one by one.