I have a dozen machines that stopped writing data (using a VB app) to my server over the weekend. I spent several hours troubleshooting the issue and am absolutely stumped. Here's what I know.

* The problem only happens on the tester machines. Older Win98 boxes.
* I can Ping the server, but can't successfully connect using the ODBC wizard.
* I've verified it's not the network drops by using my laptop on the same drop as a machine that has been failing.

The error message is 'SQL Server does not exist or Access Denied'...I ran a trace and don't see the machines trying to get access - so I'm confident the machines aren't going down the right path to find the server.

Does anybody have a rock-solid way of troubleshooting connectivity issues. Is there a way to qualify the location of the server (e.g. domain/servername) in the ODBC dialog?

I've run out of ideas and I'm not getting any help from the network folks. Can you guys save the day?