Unless "Notify on Language Exceptions" in "Language Exceptions" of debugger options is unchecked, or "EAccessViolation" is one of the exception types to ignore in the same dialog, the debugger halts the program and shows the exception as soon as a language exception is raised.
Note that according to the documentation, if the "Notify on Language Exceptions" checkbox is checked, the debugger ignores the list in the "exception types to ignore". However, this is does not seem to be the case with every Delphi verison. With my tests, D2007 conforms with the ignore list (even when the box is unchecked). With XE2, I can't make it to ignore an EAccessViolation in any way.