>I've occasionally seen something that may be the same symptom.  As best I
>can tell, MPLAB looses association between source lines and program memory
>addresses.  I had one case like that yesterday.  I know I had the right
>source module open, but the RUN TO CURSOR menu entry, for example, was
>grayed out.  I tried closing and reopening the file.  Eventually I got out
>of MPLAB, rebuilt everything (although there had been no changes), got back
>into MPLAB, and suddenly everything worked again on that same source file.
>This has happened a few times before and I've never been able to figure out
>the cause.

I have seen similar too, and came to the conclusion that it thinks a given
window has the focus (even though the title bar is not highlighted), when it
doesn't. I have recovered the situation by working my way around all the
windows, and eventually you find the one that thinks it has the focus, and
then on selecting the one you actually want, the focus goes with you instead
of staying.

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