On our test and debugging system we have the problem that our web application is not reachable under http://localhost, which is the normal path VSeWSS uses to deploy a solution.
To solve this problem we've changed the URL within the "Start Action" option from http://localhost to http://our machine's name. You find this setting under "Project"-Menu >> "Properties" >> "Debug"-Tab >> "Start Action" settings.
In or case we still deploy the solution from and to the same machine, but under a different name than http://localhost, so this might also solve your problem.