After a quick Google search I found the answer from a blog called Phatness. You can read the article here, but if you don’t want to read all the introduction over there, which was decently funny, here is what you do to fix it yourself:

1. Create a new file called DefaultKeyBinding.dict in the directory Users/%YOUR USERNAME%/Library/KeyBindings/
* Note: This folder won’t exist if you haven’t setup non-standard key bindings
2. Copy the following code into the file, and save the file
3. The new key bindings won’t take affect in any applications that are open without re-opening them

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{
"\UF729"  = "moveToBeginningOfLine:";
"$\UF729" = "moveToBeginningOfLineAndModifySelection:";
"\UF72B"  = "moveToEndOfLine:";
"$\UF72B" = "moveToEndOfLineAndModifySelection:";
"\UF72C"  = "pageUp:";
"\UF72D"  = "pageDown:";
}