Strange. if the auto-update is off, nothing should happen. Suggestion : auto-update off, uninstall Skype completely. Download old version. Run the .apk file, that should do it.
Just fixed my Galaxy Mega 6.3 to Old version
1. uninstall Skype
2. turn off auto update @ Google Play
3. restart your phone,
A number of people are reporting that the new Skype 126.96.36.199600 (16/12/13) works well on the Hudl tablet. If you find that it does not suit your needs, try reverting to an older more reliable Skype 188.8.131.5273 (tablet) or alternatively Skype Skype 184.108.40.20682 (mobile), until a satisfactory new version of Skype is released? This is what I, and many others are doing :-)