Hi All

My 98 STI Type R is suffereing from 'lumpy' steering. For the first minute or so of driving the steering feels lumpy, like the power steering is only half working. She also makes a terrible squeaking noise. After a minute of driving she's fine. This only occurs when driving from cold. I reckon it could be a belt slipping. Anyone know where to look to check this out and how much am I looking at to fix this problem?
Thanks in adavcne for your help