Then that needs to be said.
Just posting a step to do that makes no sense - unless you're detailed about why you should do it and what makes it so special and anything else that needs to be done.
In this case, asking the user to look for this file first and then seeing how large it is (desktop.ini files are tiny - that is a dead giveaway) and see if that really is the problem.
Otherwise, if the user has customized the appearance of the C:\Users folder in explorer, and deletes this file, those customizations for that folder are also gone - and if it is *not* related to a Trojan then that is just time wasted.