Ouch. I was using HAXM with Android versoin 19 quite fine. Project team wanted to use Android 18. I fell back. Now, HAXM no longer shows in AVD manager to add an AVD nor in Android Targets for project settings. Well, I can point my SDK to an old (oct 2013 release of adt) sdk and haxm is there and works. So, I totally reinstalled the ADT (20140321 version). That STILL doesn't have HAXM. Re-installed HAXM, just in case.
Anyone figure this out yet: how to get HAXM (x86 target) to show up with latest adt?