Tried to run a patch originally developed and working in 42.5 extended. I use openpanel object to load files. I used to sometimes get a dissapearing GUI (gripd) in 42.5 when i would cancle out of an open file diaglog. This time, in 43.4, the gui again dissapeared, and all of my abstractions went blank, and had a really hard time to quit out of pd. Kept getting errors about "can't talk to pd.exe" or somesuch. I may be going back to 42.5.

.. a few minutes later.
Froze up on me again, unresponsive and can't exit. This version does not seem stable at all. Also, operations that were fairly quick on 42.5 takes very long here, such as loading files, and creating tables. I don't get it.

By disappear you mean that Pd can't create those GUIs? As of 0.43.4 you need to import some libraries before create their objects with [import nameOfTheLibrary]. Can't remember the library of [grid], but give it a try.
Concerning abstraction, if they don't reside in the same folder with the parent patch, Pd must know where to look for them. You can do that either by setting a standard search path in Preferences->Path, or by using [declare]. If for example you abstractions are in a folder which is in the parent folder of you patch, you should do something like this [declare -path ../abstractions/] where 'abstractions' is a folder with your abstractions.
I wouldn't say that 0.43.4 isn't stable, I'm using it in live gigs and all is going well.

I start it with a bat file I made to open my patch, and included text from the pd-external.bat file for the loading of all libraries. It seemed to load all the objects fine. Just took around 20 seconds to create a set of tables that took only a second or two in 42.5. Loading a set of wav files took significantly longer than in 42.5, with the same patch.