I don't know what version of MC changed it, but I was looking through my library tonight (@14,000) songs, and the Date field had changed on quite a few of them to dates like 6/19/1905, 6/20/1905, 6/21/1905, etc. All years were 1905. It seemed that the day was related to a year like say 19 was equal to 1990, then 20 would be equal to 1991, etc.
I did a search through the forum and saw somebody else had 1905 years but the issue seemed to be related to the view scheme format changing. In my case, the date for some of the songs on a particular album would be correct but some had changed to the 6/xx/1905 format.
Any idea what might have caused this and how I can prevent it in the future? It wasn't fun changing a couple hundred songs dates by looking them up and replacing them.
EDIT: I tried deleting this but couldn't do it. I discovered the problem was using the Date field with the custom fields in the Lyrics Editor plug-in.