An exploratory experiment was carried out in order to question the relationships between prior knowledge, comprehension performance, on-line processes and disorientation in a non-linear document (hypertext). 14 participants read a non-linear document about a virus' infectiousness process which imposed to learners to construct themselves their reading orders and also a structure of the document. Correlational analyses were conducted to test the relations between the variables. Results indicated that the prior knowledge was positively correlated with the learning performance, the coherence of the reading orders, and negatively with the time spent to construct a document structure. Correlations between the prior knowledge and the disorientation indicated a marginal negative relation. The results stressed also significant correlations between the on-line processes and the comprehension performance. Interestingly, the observed correlations between the on-line processes and the disorientation suggested that the disorientation was function of difficulties to construct the document structure rather than difficulties to construct a reading order. The present study highlighted how prior knowledge constitutes resources to process non-linear documents and what type of on-line processes are related to disorientation.