I have a 2010 runtime database. I have installed it on numerous pc's with success and without errors. I recently encountered a problem with a couple of calculated fields initially displaying "#NAM". I am also receiving the following error when my On Timer event occurs "The expression On Timer you entered as the event property setting produced the following error. The expression may not result in the name of a macro, the name of a user defined function or [Event Procedure]. There may have been an error evaluating the function, event or macro." This pc is running Windows 8.1 and also has Office 2007. the installation of the runtime database was successful. I have included the 2 service packs for Access 2010. I can't say 8.1 is the cause but it is the OS.