After months of contacting Adobe's non-existant customer support, Premiere Pro CS4 still won't import AVC-Intra footage without giving an error message. Adobe's customer support has NEVER called me back, even though a call was promised within 24 hours every time. I have installed the update which is supposed to import AVC-Intra, but it gives the error message.
Are you running it with the latest updates - it should be version 4.2.1..
try re-naming your footage with a .mov extension.
see if that works.
not really a fix but it might work.