Windows application has stopped working.

Question

 

Hi

I have a windows application that uses webservices to interact with SQL database. The application was working yesterday but when the users tried to access it this morning it would not open. When the exe is clicked on the wait cursor appears and then a windows dialog box appears with the message "ApplicationName has stopped working".

Does anybody know what causes this and how do I fix this? Could windows updates have caused this?
We did roll back the machine to a time when the application was working but still no luck. The same application is deployed to many machines and none of them work now even though it was working yetserday and most of them use Vista.

Thanks in advance.

Thav