Hi, Kelly, in response to your question about working with network data, I generally try to keep network paths as short as possible, or at least make the connection through Windows Explorer as near to the folder containing the data you are working on as possible. It's more efficient, and also less likely that network traffic will interfere with your operation on the data.
Working with shapefiles specifically, I do not know why, but shapefiles are 'discontented' if placed in a folder named "temp", "TEMP" or any variation thereof. They are also 'discontented' if there is a folder with that name ANYWHERE in the path to the shapefile. The data simply does not behave properly for certain operations.
The issue with joining a feature class to a DBF table could be differences in the item definitions - a feature class in a geodatabase can have field names longer than 10 characters, the Short and Long Integer fields are slightly different lengths, etc. Joining a DBF table to a shapefile on the other hand pretty much insures that the field names and field type definitions will match, since the attribute table for the shapefile is another DBF.
I hope this is helpful, that you had a lovely Christmas and that the coming New Year will be the best ever.