An ICT qualification with coursework tasks so difficult that even experienced teachers find them "impossible" is leading many schools to quit the subject altogether.
OCR's AS-level is currently under investigation by Ofqual, one of 11 cases from a troubled exam season condemned by prime minister David Cameron as unacceptable last week.
ICT teachers have sent a list of complaints to the watchdog about the qualification. They include mistakes in this year's coursework marking scheme which led OCR to direct them to mark correct answers as wrong, with adjustments to be made later.
But it is the sheer level of difficulty in some of the coursework tasks that has proved the final straw for around 50 schools understood to be dropping the AS-level.
Many of them are taking even more drastic action, according to John Castleford, who has been gathering ICT teachers' concerns.
"At least 20 have been told (by school management) that ICT is not worth having if it is going to be like this," said Mr Castleford, head of ICT at Robert Smyth School, Market Harborough. "It is pulling down schools' results and is too much stress."
They say the coursework, which accounts for 40 per cent of the qualification, requires a disproportionate amount of teaching time.
Paul Long, a former OCR principal examiner who has set the coursework in previous years, said the current version took 50 per cent too long to teach. He added that teachers were having to go on courses just to understand questions "inaccessible to most 16-year-olds".
"Something has gone seriously wrong - there are so many schools complaining about it," he said. "This used to be a very popular qualification, but a number of centres are moving away because the structured tasks have become so difficult."
Mr Castleford said some of the coursework required programming skills suitable for a computing rather than an ICT qualification. Another was dependent on technical equipment many schools did not possess.
One teacher at a sixth-form college in the Midlands said all of his students had decided to drop A-level ICT because of the AS-level.
"Not only has a cohort of students been switched off ICT, but an ICT department's reputation (has been) tarnished and teachers' careers put on the line," he said. "An unacceptable state of affairs."
Another teacher said the coursework demands "exceeds what would be expected in industry". And a head of ICT in south London said a maths graduate had to help him to develop the formulas needed for one of the tasks.
Teachers have been particularly annoyed because draft tasks produced for next year's candidates appeared to be just as difficult.
But speaking after a meeting this week, Mr Long said the board now appeared to be listening to their concerns.
An OCR spokesperson said: "There is no statistical evidence that the tasks are inappropriately difficult. As with all good assessment, it is important to ensure that discrimination between candidates is achieved. In order to establish this, certain parts of the structured tasks are aimed at A-calibre candidates, and other parts are aimed at the lower grades."