Hi. I should add a little info here about my system. It is a homemade machine with an AMD 6 core FX processor running 3.3GHz. I have 16GB of DDR3 Ram. I am running Windows 7 pro 64bit sp1. The history of this issue is I was using LR 3.6 64bit successfully to make my mp4 movies using the Fit-To-Music feature for many years on this machine.
What I have been doing is sky photography. I set my Canon 8Mpix Rebel XT on a tripod and set it to continuous 30sec exposures all night. (I rigged a power supply to the 6 AA vertical hand held attachment I have on the camera, as batteries don't last all night!) I accumulate upwards of 1200 .CR2 raw photos on a longer winter night. This totals around 8GB of photos that I import into LR. I trim off what I don't want and adjust the shoot as I see fit. I then proceed directly to the Slideshow module. I select Widescreen and turn off all extraneous stuff such as titles etc. I then I open the Playback section and check Soundtrack and click Select Music. I select an mp3 file, typically 2-6 min. in length. Before clicking the Fit-To-Music button, I go down to Slide Duration section and slide the Fades down to 0. I do this as I remember having some problems leaving it at the default 2.5 sec.. I then click the Fit-To-Music button and the Slides time typically goes to 1 or 2. (If I am doing only a part of the night, say 3 or 4 hundred photos, I will get higher Slide times than that. In that case I am always successful in adjusting the Fades up from 0, even to the extent of bringing the Slides time to 0, once I click the Fit-To-Music button to refresh.) I then click the Export Video, set the name, location and video quality, (typically 1080p or 960 x 540 for video challenged machines), and let her rip. The entire set of photos matches up with the music length, exactly, every time.
What I did that I think might be the source of the problem:
I installed LR5, leaving LR3 installed. Even though I like some of the added functionality in LR5, I found I could not perform the same above feat in LR5! It was a different problem and I spent some time searching for answers, but I knew LR3 worked, so I "figured" I would use LR3 for this particular function. Well much to my chagrin, now LR3 has the above problem.
What I have tried:
I uninstalled LR5, via the Control Panel. No luck.
I uninstalled LR3 and reinstalled. No luck. The uninstall left behind stuff in the file system, including the folder:
I renamed it prior to reinstalling LR3, to cause it to rebuild. No luck.
To recap what I said in my initial post. My 2-core laptop with only LR3.6 installed, works fine. Trust me, I will NOT be installing LR5 on that machine until I find out what is going on! I may have to see about doing some forensic work in the registry to remove all remnants of what LR5 might have left behind there. But I thought I would see what you people might come up with.
Ops. I made a mistake in my description of the settings for Fit-To-Length. When I said The Slide times go to 1 or 2, I meant 0.1 or 0.2, and so forth.
Another thing I might try is using a more aggressive uninstaller, such as Revo-Uninstaller Pro. (As the free Revo-Uninstaller only identifies and uninstalls 32bit apps.) In its more advanced setting it scans for leftover items in the registry and file system, giving me the option to remove them.