I have lodged the problem with Autodesk, the Development team are looking into it.
The problem occurs on all operating systems.regardless of 32 or 64 bit versions.
There appears to be an underlying problem with the way 2010 ACA handles files in the PN. I have also noticed that if you create a sheet and amend some of the properties through the PN i.e. revision. Then open the sheet. The project name and number won't refresh on the title block.
Lets hope it Autodesk can sort it out soon. It doesn't appear have anything to do with your templates.
No solution yet, other than checking and altering the date manually (not a great solution really). I'm hoping Autodesk will resolve this issue in the next release, I can't imagine them releasing a patch so late in the year.