mineis doing the same thing.  it dindnt used to butis now and is gettingworse. i can no lnger edit contentin textboxes like this - when selecting thetextbox it just hightlights yellow anddies not select the chosen area.
i press backspaceonced no worries' but thesecond time thewhole text typed dissappears an except the word i am backspacing. very frustrating.

 sorry forall errors' i fear trying to correct them will mean spening several rewrites just to get itright.

If I press backspace just once it deletes one letter, then pressed once again even several seconds later it deletes the whole text box of text.

PLEASE HeLP!,,,,,,