I don't know how many people are still using 8.5.3, and I doubt anyone else has had this problem, but:
 
I enter a MIDI note, either on the piano roll or by playing it on keyboard . . . and it sounds twice. If I enter a quarter note, I hear what sounds like a 32nd note first, then the quarter note. The piano part was almost done. All I needed to do was add this note. And this problem cropped up. All the other MIDI notes sound fine. I can't figure it out.
 
I realize asking is a long shot, and I have to finish this project right now, so unless someone currently on the forum happens to know the answer I'm out of luck. Anyway, thanks for reading.
 
Dang, it's weird.

Wish I could help with any certainty, but i figure posting helps keep this near the top :). I uninstalled 8.53 long ago, but a good number of people still use regularly. Several possibilities jump out as possible. Check echo settings and your synth rack to see if you are triggering multiple synths. Also check if the track or synth has any arp type settings or plugins enabled. Even a midi effect like a simple midi delay could cause such things.

Thanks very much. Those are all better ideas than I could come up with. I'll give them a try.

+1, if you enter only one note in PRV and get an "echo," triggering multiple synths is a good one to check. If that MIDI track is set to use "MIDI omni" every active synth will receive/play that note. Try changing the midi channel to 1 on both the midi track and synth. Beware of "MIDI omni."

fpoir
Thanks very much. Those are all better ideas than I could come up with. I'll give them a try.

Good luck.  I know how frustrating things like that can be.  Hopefully some 8.53 guru will come along soon.  One thing this foum tends to be is very helpful. 

mettelus
+1, if you enter only one note in PRV and get an "echo," triggering multiple synths is a good one to check. If that MIDI track is set to use "MIDI omni" every active synth will receive/play that note. Try changing the midi channel to 1 on both the midi track and synth. Beware of "MIDI omni."

Thanks. Another great suggestion/tip.

dubdisciple

fpoir
Thanks very much. Those are all better ideas than I could come up with. I'll give them a try.

Good luck.  I know how frustrating things like that can be.  Hopefully some 8.53 guru will come along soon.  One thing this foum tends to be is very helpful. 

Thanks. And thanks for the help.

You didn't mention if the keyboard is a controller or also makes sounds, but check to see if Local Control is off at your keyboard. If it's on, turn it off.

Thanks. Will do.
 
Your writing's been a big help to me over the years.

fpoir
Your writing's been a big help to me over the years.

Thanks much   Seems like I've found a new home for some it here!