I've had this problem ALOT actually. I have this happen mostly with BB Messanger and what will happen is when I type and then hit the space, nothing will happen so I hit it again and it will do the double tap and period. If I try to type again, I get a input error message and the program shuts down. I've had this issue many times and had gone through quite a few handset wipes and still experienced this.
I just received a new phone from Verizon though, and have installed the OS4.3 so hopefully this will stop.
...although with the number of exchange pearls I have had (four since December) I would tell verizon that they need to get me out of the pearl, maybe then I could get into the Curve for next to nothing!!