A low level exception occured in: Importer MPEG (Importer)

Okay, first some system specs:

Macbook Pro

2.2 GHz Intel Core i7

8 GB RAM

Radeon HD 6750

OSX Lion 10.7.5

Premiere Pro CS6 (updated to lastest available version)

--I remember installing updates a few days ago (maybe last week), but don't remember if any of them were for Premiere and could possibly be the problem.

The trouble I'm having is with one .MTS clip. I have a timeline about 20 minutes in length. I edited the whole thing and had no problems the whole time, with any clip. All clips originally imported correctly, played back fine, etc.

I exported a copy for client review (from Media Encoder CS6) the other day. One clip (the .MTS clip in question) showed as "Media Offline". It is not offline, I did not move the clip, etc. I unlinked the clip in the project, relinked it, and it did show up in the project and was able to be played back.

Exported another copy, found the same error occured with just this one clip. Now I'm noticing that when I open the project, I receive the error in the topic title (A low level exception occured in: Importer MPEG (Importer). The clip will not play back and shows up as "Media Pending", as if it's not coming in correctly. Unlinking and relinking doesn't fix the issue.

I have many other .MTS clips in my timeline. All of them work correctly, play back correctly, and export correctly. There doesn't seem to be any inherent problem with the clip itself; it plays back smoothly in VLC, and I've transcoded it to a .mov to try and just bring that in and get around this stupid issue. This didn't work either; I unlink the clip, then relink to the transcoded .mov -- it actually will play back in the preview monitor, but will not display when trying to view it on my timeline. I have also created a copy of the project, tried this inside of the copy, as well as created a new sequence and pasted over the information; none of that worked either. There are also other sequences this clip is on, and it will not play back in any of them either, but as I mentioned, plays back in the preview.

I did find one other topic with a similar issue; they recommend deactivating Premiere, restarting the computer, and activating it again. I did do a restart initially to try and diagnose the problem, but to no avail. I tried deactivating the program, but the Adobe Application Manager doesn't load; it has almost never loaded for me whenever I try to use it, which is frustrating in and of itself.

I tried creating an entirely new project and importing the other project. When I did this Premiere just froze; I'm assuming it can't handle all the pieces (it's a fairly complex project with hundreds of clips) and they are also coming off an external drive through a USB 3.0 cable.

I've temporarily "fixed" this by bringing in the transcoded clip, resyncing it to to the spot I need it in, and cutting it as necessary. I typed this post as I went and tried various things, and while I've found my way around the problem, it doesn't really solve it. I opened another old project that was very similar to this one and also encountered the same error message. I didn't stick around to find out if there was just one clip causing the issue; the fact that it was there was enough for me.

So, what do I need to be doing here? I'm guessing the stock answer is to uninstall Premiere and reinstall it, which I don't want to do unless I have to since it's a pain in the ass. I'm kind of through the problem for this project, but want to be able to deal with it for the future. Hoping someone with knowledge can chime in and tell me whether it's the update from the other day causing this.

If the answer is to uninstall and reinstall Premiere, do I need to run some cleaner tool? I vaguely remember hearing about that before in regards to uninstalling and reinstalling.