Mumbai, April 30 (IANS) He is a southern superstar. As Vikram steps into Bollywood at the age of 44 with 'Raavan', he is acutely aware of going where perhaps no Indian actor has gone before - playing the hero in the Hindi version and the villain in the Tamil edition.
He admits to being initially scared to be part of the Hindi version of director Mani Ratnam's 'Raavan' but says his co-star Aishwarya Rai's brilliant performance in the Tamil venture boosted his confidence.
'Initially, I was very scared because I had this mental block. What kept me going was that Ash didn't know Tamil and she was doing so well,' Vikram told IANS in an interview.

Please explain to me what "mental block" means here.

Source : http://in.movies.yahoo.com/news-detail/86939/Ash-inspired-Hindi-Raavan-Vikram.html
Have you ever tried ? It may be useful to you as it has definitions of lots of English idioms. In this case it helps out with:

to have a mental block = to have some psychological barrier that prevents one from doing something
Thank you Mr. Wordy as usual.

I do use different dictionaries before I ask here in our Englishforum but sorry this time I never thought "mental block" was an idiom expressing a distinct meaning. I was just thinking "block" was a different word and so "mental" that were used together in a figurative way.