AVI is only a file wrapper... what codec?
You might work through all of the steps here http://ppro.wikia.com/wiki/Troubleshooting
If your problem isn't fixed after you follow all of the steps, report back with the DETAILS asked for in the questions at the end of that link
The first question has links to software that will give you the details about your file
I'll try this things.
It's interesting that the video plays fast while the audio is normal.
Report back with the file information... the codec inside that wrapper
What you describe is USUALLY caused by a non-edit codec that is designed only for playback, such as xvid/divx or some other COMPRESSED codec hiding inside that AVI wrapper
If that is the case... the solution is to convert to a "real" AVI of DV AVI type 2 with 48khz sound
I've imported a video clip into Prem. Pro CS4 in .avi format.
Where did you get the video clip?
There are many oddities, when certain CODEC's are used to create the AVI files. Some CODEC's, like DivX/Xvid will Import with NO Audio, or NO Video. Other times, the sync drifts all over the place.
Other "delivery" CODEC's refuse to edit at all, though they can play fine in some media players - editing is very different than playing.
G-Spot is your friend, as mentioned in my link. Use it to tell you (and us) all about those .AVI files. The problem is most likely the CODEC used to create them, and it not being one meant to be edited - only played.