Stephen Thomas suggested Using 64-bit Access 2010? You may want to wait on [Installing] SP1 in a 7/8/2010 post to the Access blog:
The database cannot be opened because the VBA project contained in it cannot be read. ... To open the database and delete the VBA project without creating a backup copy, click OK.
On clicking OK, Access doesn't open the database, offering this error message:
The code contains a syntax error, or a <DB_NAME> function you need is not available. If the syntax is correct, check the Control Wizards subkey or the Libraries key in the <DB_NAME> section of the windows registry to verify that the entries you need are listed and available.
Apparently, the VBE7.DLL file update included in the service pack prevents the opening of .ACCDE files compiled using RTM 64-bit Access. Because wizards are .ACCDE files, they could trigger the error depending on when they were compiled.
The customer who posted reports that uninstalling the service pack restores the functionality, and advises that people with 64-bit Access wait until a solution is provided before applying SP1. TechNet agrees (the mod marked it as an Answer), and so do I.
Stay tuned for that solution…
Forewarned is forearmed.