Personally i dont think the degree would hinder the chances of your friend getting the job. People change their career paths all the time so there are various reasons for wanting a job different to whatever has previously been studied for......
I have spent much time in the past temping (in admin) and in between i have volunteered at various places, so i also have a patchy history. I also walked out of a job in May but because i spoke with HR about the reasons, i was given one months full pay and i am now working for them again in a different department altogether.
I think, as long as the application form is satisfactory and questions are answered fully in interview with a full understanding of the requirements of the job, your friend stands as equal a chance as anyone. In admin its a good idea to mention organising skills, good time management and prioritising workload, as undoubtedly these will be the areas focussed on. Hope this helps...