Windows security expert required

I am looking for a windows security expert. I have a chat site and some competators is doing something on user's pc so that they can not enter my website. When my users try to enter, the system complaints about 'An add-on for this website failed to run'. So they are doing something to the browser settings or something so that it disallows users from entering my chat. I want someone to find the problem and write a .dll or .exe so that my users can run to fix the problem on their PC.