Basically, I'm trying to put this Korean drama on my HDD. The whole series is AVI, but for some reason, after episode 2 none are supported.

So, what gives? Does it have to be a certain resolution? Bitrate??? I'm 100% lost.

It might depend on what codec is used

It is most likely the codec. There are always some files that do not play. If they play on your PC you might try to reconvert them but thats a very time consuming business.

It's probably the same as Xbox360 where some codecs aren't supported. I have 4 avi files which didn't work out of 30. Perhaps there'll be an update, I'd give it some time.

You could re encode your avi files but if you ever plan on converting them to DVD then I'd keep the originals to minimize further video/audio degradation.

How do I check what the video codec is? The PS3 will tell me the episodes that work are MPEG-4 1.3 Mbps, but it wont tell me what the ones that dont work are.

Actually I remember, the PS3 used to read them as MPEG4.

What happened was, I used AVIAddXSub (makes a DivX file w/o re-encoding, basically adds subtitle support).

Then I plugged my external hard drive in, made sure that the DivX file worked, then I proceeded to delete the original MPEG4 files, and that was when I noticed a lot of them suddenly became unsupported, where before they were read as MPEG4s. I never played them, but at least the title and the little grey box on the right saying "MPEG 4" showed up.

And unsurprisingly, the DivX's associated with the now unsupported AVIs dont work, but the DivX's associated with still working AVIs still work.

So... wtf???

Using something like VLC on your PC should let you know exactly what codecs are used. Supporting 'all' AVI files are next to impossible as AVI is just a container format which can contain almost any codec ever created. In addition to that it could be that your AVI's are slightly broken and the PS3 is relatively picky on having proper AVI files. while some PC software like VLC go out of their way to try to play even the most broken files. (The major reason for not trying to support broken files is probably because it also increase the chance of your playback application crashing quite a lot, and thus is pose a security problem.)

According to WMP, it is:

The audio codec doesnt come up, but video is

CyberLink H.264/AVC Decoder (HP_NB22)

And I found the ones that work are all:

DivX Decoder Filter

If you're not too concerned about quality, you can even try run them through a windows movie maker session.
It's far from perfect, I know, but it's a quick fix that works 10/10 times for me when i run across a codec for a "home movie" and i couldn't be bothered to sit and fiddle with codecs

either that, or stream them through Tversity or something with a transcoder