Yes, there is an upper limit on the number of layouts you can have. I don't recall the exact number, but it's a lot more than 100. Organize your layouts into folders and you should be okay.
I believe this is a bug in the windows version of FileMaker.
I have the same issue on my windows computer, but when I use my Mac in the same database I am able to select any layout without it jumping to the last one.
Is there a limit to the number of layouts one can create in FMP 11?
You are only limited by disk space or maximum file size... there is no specific maximum number for layouts allowed.
(hint: it's 11 up from the bottom of the list)
Yes, this is true. You can create any number of layouts. However, the issue Dave is describing is a known issue with the number of layouts appearing in the Layouts Menu; see: