By default, in Apple OS X, when you type “…” (dot, dot , dot) and press [space], the three dots get converted to a single unicode character, ‘…’, which can cause problems in some scenarios.
There are several mechanisms involved for this feature, making it difficult to disable in some versions of OS X or in certain applications, if you don’t know where to look.
Since OS X Mavericks (10.9) most Apple apps have the menu option, Edit -> Substitutions, wherein Text Replacement and other auto-type features can be turned on or off, though oddly not just for the app in question, but system wide …
But what about all those non-Apple apps or earlier versions of OS X, that don’t have an Edit -> Substitutions menu item?
As of OS X Mavericks, the ‘dot,dot,dot’ feature specifically, is an auto-replace item, found in System Preferences -> Keyboard -> Text. You can delete the ‘…’ item entirely.
In earlier versions, there is System Preferences -> Language and Text ->Text. Then un-check the ‘…’ item.
Note that since Mavericks, these auto-replace items are synced across all your devices, via iCloud. So removing the ‘…’ auto-replace item on your Mac will also remove it on your iPhone, iPad, etc.