This looks to me as though the APE tags do not contain any useful data.
So before reading the files, switch off the reading of APE tags and you should see only that what is in the V2.3 and V1 tags.
This data should be complete (according to what you have written).
Then save these files to get rid of the APE tags and that's it.
Alternatively, you could launch Mp3val as this program usually interprets APE tags as "garbage at end" and deletes them.
ok ... I've already read and deleted (top left-hand corner buttons) the library I used from the back-up with the options previously suggested so I might've prevented that option on this PC.
So, I'll use my 2nd laptop to test out your theory with the same HDD back-up.
before I try it, let me be clear, my options will be set to
READ ID3v.1 and ID3v2
WRITE ID3v2
REMOVE ID3 v1 and APE
I'll highlight the songs containing APE, then I'll press Save in top-left...and then the X delete...
UPDATE: I tried the options above and it left some data intact in MP3tag but not all. So I tried also writing the ID3v1 option ... and it worked every time on my 2nd laptop (library 6 weeks old). Great!
I was so confident this was the answer, I replaced my work of the last few days on my main PC with the most recent HDD back-up. Sadly, this is NOT working 
The tags are still visible in iTunes AND Mp3tag, but not in Windows. Not sure why the recent back-up isn't working, maybe cos I deleted a 2nd Comments field a few weeks agio? Anyway, I've tried playing around with the Save/delete options but can't get the tags to show up in Windows. If the tags are still in MP3tag and iTunes, can you think of anything else I can do? downloading MP3val now...
I'm near the end of a long mess but the strangest thing is happening.
Can someone explain it?
I have an iTunes library on an older laptop running 32-bit Windows 7 Professional.
I check a music folder containing 6 songs and Windows Explorer shows various data, inc artist, album, genre and "part of set" (the iTunes equivalent is DiscNumber) ... but no BPM
I copy the 6 songs on to a memory stick and put it into my main laptop (running 64-bit Windows 7 Ultimate) ... and it will not show "part of set" or BPM. these are very important to me
then I put the stick into a netbook also running Windows 7 Ultimate ... and it shows all the data fields, including "part of set" and BPM. These are the ame songs tested one computer immediately after the other.
does anyone know why a laptop running Ultimate misses several fields, another one also running Ultimate shows all fields, and a 3rd laptop running Professional shows some of the fields ... and is there anything I can do about it?
You can define additional columns in WE.
Depening on your individual settings, modifications of the default layout are stored or not.
Ohrenkino, I know you can select which fields you want to display in WE!
what I am saying is that even when I choose to view the same fields for the same songs in different computers, they all appear in 1 computer and several are missing in another PC.
I'm really amazed it has been some weeks since I first started posting about this. Maybe people simply can't be bothered trying to help but at least 1 other person could be helping here and clearly doesn't wish to
I can only say thanks very much Ohrenkino. You alone have tried so hard to help. This is very important to me and I'm working all day every day trying to fix it. I just seem to hit a brick wall whatever I try to do.
Oh, that's good.
So I don't have to suggest to try to switch it off an on again? Just kidding.
The problem with remote diagnosis is, that you have to first get the basics straight.
"Don't show" in that respect is a little ambiguous.
As WE sometimes gets a hickup: have you tested the files on the target system with mp3val?
(I do not know what happens on the way between the one working computer and the next one which does not behave.)
And referring to other people's help: they will have the same problem that they cannot look over your shoulder. To me, most of your problems seem to arise from local settings and assumptions on how programs should work.
As far as I can tell it has been other programs that do not do the stuff you assumed they should, starting with out of sync tags.
If you have problems with Windows and you do not like the information you get in this forum, you are free to contact Microsoft.
For the time being, I wish you the best of luck in finding a solution. I clear the field for other users.
Thanks. I believe the following information is not ambiguous. I'll ask one more time in case someone understands it. I've already donated twice to Mp3tag - most recently $50 - I'll also offer $50 if someone can solve this for me cos this has been driving me mad for weeks.
I have 6 songs.
I list them in windows explorer in 1 PC... and some fields show as empty. (e.g. BPM, part of set)
I then list the same songs in a 2nd computer, same fields ... and ALL the fields show details.
Both computers run Windows 7 Ultimate.
Anyone know why?
Workaround
Try copying the files in question to another physical drive, delete the non-taggable original files, and then move the copies back to the original location.
Radical workaround
Sometimes stripping the file of "Properties and Personal Information" helps.
Upside: the files can be tagged again without problems.
Downside: You lose all tag information.
What you can do is this: select files in Windows Explorer, right-click > Properties > Details > "Remove Properties and Personal Information".
Choose "Make a copy". You'll keep the original files and be able to at least see the old tag info in MP3Tag; you can then re-tag the new files (the copy). Admittedly, that's a pain if you have a lot of tag info already. But at least the files can be worked with again.
Hope this helps.
Regards
Karl