ASP.NET: Could not find a part of path

We have a asp.net 2.0 / 3.5 project, it worked on our development site, but when we put it to product site, all functions about file read such as used Server.MapPath() method could not work and got the error like the following:

Could not find a part of path “C:\ABC\Path2\Path3\FileTemplates\”

The solution is just set site ROOT folder a READ permission to ASPNET user. because our project deployed on the folder “C:\ABC\Path2\Path3\”, so we just needed to set READ permission for “C:\ABC\Path2\Path3” to ASPNET user.

Update:
Actually finally we had to reboot server and then got everything work.