it says "Date: 0.0416689814814815" what does this mean?
The short answer:I really don't know.
The long answer:The date value in iTunes M4A files is normally stored in the ISO format. MC converts that value to the internally used "Microsoft Excel/Access/etc" format.
In your case the tag reader in MC has interpreted the file tag value as "0.0416689814814815". In the user interface this particular value is displayed as "31 December, 1899, 01:00 AM" (in the exact display format that is defined in the Windows locale options).
However, even that is not the correct value for "0.0416689814814815". The day "zero" should be
30 December, 1899 (which is a day that does not work at all in MC). The exact decimal value for 01:00 AM would be ".0416666666666666...", but this small discrepancy is not a problem, because both values show up as 01:00 AM when the display accuracy is limited to full minutes.
In the past I have explained the internally used time system and reported the "day zero bug". You can find the links here:
http://yabb.jriver.com/interact/index.php?topic=59513.msg404286#msg404286A more important issue is the reason why the tag reader sees a year 1899 date & time stamp in your case. In my case MC apparently imports at least all year 1900+ values correctly. I wonder if some other program has corrupted the date tags. Have you edited the tags anyhow before importing the files to MC? Do all iTunes tracks show the same incorrect date, or does it vary? Do some tracks actually show the correct date? Does some other program show the correct dates?
Probably the JRiver developers would need to have a sample file.