These seem to be messages generated by Vista, rather than Epson errors... correct?

So it would seem that you haven't installed the drivers correctly.

Broadly, you need to install the drivers WITHOUT the printer connected to the usb port, and then when the software asks you to connect the printer, you do so and make sure the printer is powered on a ready (online). The software will then detect the printer. If it doesn't, it won't work, despite the fact that Epson (unhelpfully) adds the printer anyway and finishes the installation.

So uninstall what you have. Remove the printer from the usb port. REstart the machine.

Install the software and connect the printer ONLY when the software requests you do so. Does the software actually find the printer?