Some candidates don't deserve consideration

As usual every 4 months I interview a slew of candidates for internship. As per company policy I can only hire students who have a minimum of 2.6/4.0 or 2.9/4.3 GPA. I also put in the job description that we only consider students from first or second year into their Bachelors degree. The main reason is, often if they are 3rd or 4th year, they have had enough programming classes to be able to work on small development projects, but I have no such work to offer them.  I've often hired students, that after 2 weeks of doing testing, come to see us and want to do 'development'.  When you tell there there is none in their job, they stay pissed off and do the least possible the rest of the workterm.  First and second year students don't have enough experience to expect development jobs and overall tend to be a better fit in my team.

The worst internship to fill is the winter one, that goes from January to April.  The easiest to fill is the summer internship, From May to August where I get too many good candidates for the few jobs I have. To give you an example, currently I have 6 positions to fill and I got 15 applicants. I had to brush off 5 candidates because they did not meet GPA requirements, despite the fact that on our job description, it clearly states the minimum GPA we accept. For a summer internship I could get 100-150 resumes for the same 6 positions. [Then I screen via GPA and if they have finished more then 2 full years of University]

Since I had 10 candidates left after screening, I just chose to interview all of them. Generally I don't spend much time reading cover letters as the majority quote at least 1 paragraph from our corporate website which tells me very little about them. The resume itself I skim through to get a sense of prior jobs and experiences. Generally though I base my selection of candidates on candid responses in interviews and not much on their writings. 

The first candidate we interviewed apparently seemed surprised that we were interviewing for winter semester, and was looking more for a summer job.  I'm not sure why I would interview students for summer in OCTOBER!!!!  Then just to make things interesting he proposed a schedule of the hours he could work on 3 days a week!!!  I'm not sure how I can use a student that comes 3 hours here and 4 hours there. I can use a student like that AFTER they have been with us full time for 4 months and were exceptional in anticipating the jobs needing to be done.

I thought I had just run into a clueless postulant. I wasn't so lucky. Today I got 2 more resumes from this particular university, and when I was looking for the students GPA, I realized both students were registered for winter classes according to their transcript.  One clearly say they want a winter internship, but I'm not sure how this applicant would manage it if they are registered in no less then 6 classes in Winter 2013. The other had no cover letter, and in really small print on their resume said they were looking for Summer internship.

I was so disappointed that I asked my HR person to contact the schools internship coordinator and ask why students with a full course load are applying for internship positions.   These are not part-time jobs after school hours. This is a full-time position between 9-5pm, 5 days a week. I have no interest in wasting time to see a student who I cannot hire full time for Winter 2013.

I can hear someone argue with me that I'm being inflexible. Perhaps, but the internship I have to offer is in quality assurance.  It is of utmost importance that the candidate knows the difference between a failure and a success.  If a candidate cannot follow simple instructions, how can I trust them to put quality into a product in a timely fashion?