Graham Lock (1996) in the course of learning a second language argues that learning a second language is hard work and for most people involves a considerable commitment of time and effort. The work may sometimes be enjoyable, but learners do not usually undertake such a task without the expectation of a pay off. Moreover, a lot of barriers have been found for language learning. According to Ely (1995), the word ‘uncertainty’ denotes a feeling that for most people is not particularly unpleasant. This mental state is, however, commonly experienced by ESL learners, and it is a feeling that may inhibit students’ risk taking and interfere with their acquisition of new learning strategies. For ESL students who are participating in an unstructured role play situation or working in pairs to produce a written dialogue, the opportunities for uncertainty are endless: “Do I use past or present perfect here?” “Will that word I learned work in this sentence?” “Am I pronouncing the letters /ch/ in ‘chief’ as in the word ‘chef’?” Therefore, tolerance of ambiguity merits consideration in teaching ESL. If a student experiences a feeling of threat or discomfort when confronted with a linguistic uncertainty and is less inclined to take risks, learning may be hampered. Therefore, among the factors hampering learning, we can refer to affective factors as the most influential. The present research study was a case study to investigate the problems found to be the barriers to language learning of an EFL learner and the introduction of intervention programs to tackle with those problems. Maryam was a student at university who was found to have severe difficulty in language learning. Through applying the questionnaire of tolerance of ambiguity she was discovered to have suffered from factors to do with this affective factor. The intervention programs designed by the researcher helped Maryam to get over the problem and improve. The data analysis of the pre/post tests confirmed the assumption made by the researcher.