Now() uses / to seperate the day/month/year. Unfortunately / are also used as path seperators for folders.

So when you say

[VBA]SaveAs ThisWorkbook.Path & Rename[/VBA]

You are really saying

[VBA]SaveAs ThisWorkbook.Path & m/d/y...[/VBA]

And of course those folders do not exist. What you need to do is specify the format and do not use /.

[VBA]Format(Now(), "dd-mm-yyyy h:mm:ss")[/VBA]