If you continue to have upgrade and/or uninstall problems, our installer guru suggests the following:
Go to Add/Remove Programs, select NI-VISA 2.5, and try Repair and then Uninstall. After it is uninstalled, then you should try upgrading to 3.1. For most folks reading this, these steps aren't necessary. Somehow your system got into an odd state, and hopefully the Repair should bring it back into a stable state. Dan Mondrik
