I realize how vague this question is going to be, unfortunately I'm at the end of my rope in trying to solve the issue.
My company has a .net 2.0 app we wrote. It uses Microsoft SQL Server for it's database. We have been deploying it with no issue for a long while. Our most recent deployment had the Database installed on MSQL Server 2014, it was originally created on 2005. After the installation of the database, and the installation of the client application, the program runs great for about 4 days. After those 4 days, it takes about a minute to log in (Using ASPNET) After log in some of the data pulls do not work. For example the main screen gathers a set of records based on the user who has logged in, this list won't populate. However if you open the screen for assigning the user to those records, the records and the user assignment populates with no issue. Of course with the weird data problems, the app is running incredibly slow. This also has never occurred. The installation in question is on Windows 7 and 10, both OS's we have installed to before with out incident.
Any thought on a possible direction for troubleshooting this would be appreciated, I have hit it from several angles with no luck.
Thanks again.
So the answer to this problem was to turn on ANSI nulls in all of my stored procedures. Due to how vague my question is I'm not posting this as an answer. However the issue is resolved and I'm adding this comment for the sake of completeness.