Do this one at a time and test the operating system. Shut down and re-start to make sure that the problem doesn't reoccur after you add each program. If the problem comes back, it is easy to trace the problem back to a particular program and make necessary corrections. The final step is to restore the data files from the backup, and again check the system to ensure proper operation. Software, on the other hand, is affected by many different things.
Some programs can cause incompatibility with other programs.
One program can install a DLL file over an existing DLL causing a previously installed program to run improperly.