Word 2007 Mail Merge Add-In installation problem

I'm getting an error when attempting to install the Add-In into my Word 2007(see details below). I noticed that it never asked me to login with my Postal Methods account as indicated in step 5 of the installation instructions. I also tried running the installation file as administrator. I've also tried uninstalling, rebooting and reinstalling. Each attempt comes up with the same error message listed below. Any guidance would be greatly appreciated.

Regards,
James
james.stapleton@1stRatePoolService.com

Error Message Details:
Name: PostalMethods Word Mail Merge Add-In
From: http://www.postalmethods.com/files/clients/word2007_mailmerge/PostalMeth... Word Mail Merge Add-In.vsto

Specified argument was out of the range of valid values.
Parameter name: entryValue

************** Exception Text **************
System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
Parameter name: entryValue
at Microsoft.VisualStudio.Tools.Applications.Deployment.RegistryStore.Retrieve(String entryName, Object entryValue, CompareDelegate compareMethod)
at Microsoft.VisualStudio.Tools.Applications.Deployment.MetadataStore.UpdateLastCheckedTime(String subscriptionID, DateTime newLastCheckedTime)
at Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInDeploymentManager.InstallAddIn()