RESOLUTION 1:
1. Open the command prompt window and type in PATH and press enter.
2. Check to see if the Oracle client being used is in the front of the path. If it is not, then close all windows and do the following:
a. Right click on My Computer and select Properties.
b. In the Advanced tab select "Environment Variables" button.
c. In the System Variables section, highlight Path and press edit. Edit the path so that the Oracle client's bin directory is first.
For example: PATH=C:\oracle10g2\BIN\;...
3. Launch Visual Studio and re-test the connection.
RESOLUTION 2:
Ensure that the connection being referenced is in the TNSnames.ora file of the default Oracle client being used.
