Paltrow spoke about the differences between film and stage acting

"I used to be excellent," she said. "But now I have a baby and I couldn't tell you what day it is."

The Hollywood star also revealed that some of her male co-stars have been "a real pain in the ass".

Paltrow, who gave birth to daughter Apple in May 2004, was speaking to students at London's Central Saint Martins Drama Centre on Thursday.

The actress discussed the differences between stage and film acting with the centre's director Vladimir Mirodan.

"In the theatre you need a sense of security, but in film you don't want it," she said.

I don't like to watch myself on screen - it makes me freak out Gwyneth Paltrow

"Film is all about capturing the moment. You must have spontaneity; otherwise you can see the wheels grinding."

She also revealed the difficulties involved working with Jude Law on Sky Captain and the World of Tomorrow, which used computerised imagery instead of sets.

"It's a strange experience," she said. "You're trying to make things as real as possible, so it's daunting when it's so glaringly obvious it's all pretend."

'Insecurity'

Selected clips from Sliding Doors, Shakespeare in Love and Hook, one of her first films, were greeted with mock horror by the 32-year-old.

"I wish I didn't repulse myself so much," she said. "I don't like to watch myself on screen - it makes me freak out."

Paltrow starred with Jude Law in Sky Captain and the World of Tomorrow

She also explained that her sensitive nature can make her vulnerable on set.

"I don't know if it's a blessing or a curse," she said. "If I walk into a room and somebody is in a bad mood or upset I can feel it.

"I end up taking it personally when it's nothing to do with me. Maybe it's just old-fashioned narcissism."

And without naming names, she revealed that two of her male co-stars had been difficult to work with.

"It has to do with their insecurity," she said. "It's about managing this other person and making them feel they're okay and that you know your place.

"With one guy, managing him was my primary job," she continued.

Paltrow recently returned to work to star in Running with Scissors, in which she plays the daughter of a psychiatrist with mental problems.