The initial installation, setup and activation of Microsoft Project can raise issues and we see quite a few calls on this topic, so wanted to put together some links that might help – and save you having to call Microsoft. Often the issue relates to a clash of versions or sku’s, and sometimes it may be due to a version of Office that came pre-loaded – the Office 2010 Starter. Hopefully these links will help – along with links to resolve common issues such as a message about invalid product keys, or if you have lost or damaged your Office 2010 product key. First some wizards to help with product key problems: Are you receiving an invalid product key error in Microsoft Office 2010? - http://support.microsoft.com/kb/836178 How to replace a lost or damaged Microsoft Office product key - http://support.microsoft.com/kb/823570 If you are using Volume Licensing and MAK key then this is a good blog posting to read - http://blogs.technet.com/b/odsupport/archive/2011/04/15/getting-invalid-product-key-error-when-trying-to-input-mak-key-for-volume-license-version-of-office-2010.aspx . Another common question is around side-by-side installation – either where Project is being installed with another version of Office (such as upgrading to Project 2010 but still using Office 2007) – or even having multiple versions of Project on the same system. The best guidance here is firstly only do this if you really, really need to, and to install in a separate directory, and the first thing to try if any errors are seen is to repair the original installation. For example if you load Project 2010 and then see any issues with Office 2007 – run a repair on Office 2007. With multiple versions of Project there is another potential issue – and that is which version should start when you click on an mpp – and the rule of thumb here is that the last one installed will win. So either install to ensure the one you wish to be the one to load mpps is the last one – or run a repair on the one you want to be considered the ‘current’ version for opening mpps. You can also set the default version via Control Panel, Programs, Default Programs, Set Associations – select mpp then Change program and browse for the specific winproj.exe in whichever directory you loaded the version you wish to open mpps. Another consideration if working with side-by-side is that there have been some behavior changes in the various releases – so it is best avoided to keep moving plans back and forth between versions.