Premiere has suddenly stopped importing avi/mp4 files

Question

I am using Premiere Pro CS3 on a mac.
With no explanation, Premiere has decided it can't recognize files that it recognized fine a few weeks ago. I have projects that I've already finished and when I reopen them it says the media is offline. When I attempt to import .avi files I get either a "codec missing" message or an "unsupported compression in file" while an .mp4 gets me "unsupported format or damaged file"
while I have "fixed" the mp4 issue by changing the file extension to .mpg, I still cannot import any .avi files, which didn't use to be a problem. Also I didn't have to change the file extension on .mp4 files before, either.
I am extremely frustrated and have no idea why nothing works except using another program to turn the .avi files into DV format, which for some insane reason makes a 20 minute video 3.95 GB, which makes me think somehow I'm doing that wrong too.

Answer 1

>That seems ridiculous
No, that would be trying to edit a delivery format
You are an artist - You paint on a canvas
It is a FLAT canvas where you may see and paint everything
That is similar to Premiere with a DV AVI type 2 file... it may see and paint (edit) everything
1-Now, read here to see
Why NOT to try and edit an MPEG
Your canvas is now "fan folded" like the expanding part of an accordian You may now only see the edges of the folds - You may NOT see inside the folds You are now trying to paint a full picture based only on being able to see those edges
That is similar to Premiere with any variety of SD (StandardDef) file compressed into an MPEG (HD "HiDef" is different, with it's own set of issues and problems)
Do not be fooled by movie industry advertising into thinking that "DVD Quality Video" is suitable for EDITING... it is not... a DVD is for PLAYBACK only!