try booting up in safe mode
(hit the F8 key before the windows logo comes up
) and the rapi.dll won't be loaded and should be easily deleted.
I went through the same hell some months ago...I am back to AS 3.8 because I prefer to use WIFI
(less secure I guess
) which is eliminated in AS 4.5
( #@%&!!! Microsoft
)
all the best