I think (but can't be sure without seeing the data) is that you'd want to add an extra clause to your WHERE in the nested selects.  You would want to...

To me, your solution sounds more like a workaround to me.  Or did running that once fix the log growth issue?

I'm just thinking that to me, your solution...

Depending on how they need to share the data, you could have a new database per city.
likely not an ideal solution, but it is another option.

a new...

If you have an MSDN license, you could just spin up a windows 7 VM for testing it.  Since you didn't use WPF, I can't think why it wouldn't work...

Was just looking at the application and I am a little confused about it.  

At the moment, I am not sure how this is much different than just...

Can we get some DDL and sample data to work with?
The way that that is now, I don't understand what the data looks like nor why you'd need a...

We actually have that set up where I work.  Although we use a 3rd party tool called DxEnterprise (I do not work for them).  If you have used Polyserve before,...

Then I am not sure.  Sorry about that.  I've not seen that before except when I end up with an unnamed column.
Any chance that 2 columns ended up with...

Without seeing the data, I would try something like:
BEGIN TRANSACTION;
SELECT MISCCODE FROM table;
UPDATE table
SET MISCCODE = MISCCODE + '1'
WHERE MISCCODE NOT LIKE ''
AND...

are your columns named?

That is, if you are using aggregates, are you providing an alias to the column?
Like a "SELECT SUM(dollars) FROM table" won't have a column...

Has this ever worked?
Is there a different SQL instance you can successfully connect to on the network from your local machine?

I may be mistaken on this one, but I THINK the service account not being able to talk to AD can cause that problem too.
Might want to check that...