You have tables that have a lot of data inserted into them and deleted that use identity values and run out integers to use. I have over 3000+ databases where this can occur so we have an alerts setup that checks the tables then checks a table to see if setup to be auto reseeded based on rather of database engineers have indicated it is safe to do so. If it is that table is auto reseed either to one the maximum negative number for the datatype else we are alerted and we check with our database engineers on how to handle that table. Keep in mind we are reseeding tables that have been deemed OK to reseed automatically.
Click through for the code, which includes reseeding logic, a job to run reseed operations, and a whitelist table for the tables which you want to allow automatic reseeding.