20D In-Camera Meter Failure?

I was out shooting a baseball game and had borrowed my friend's 70-200 f/2.8 IS on my 20D and all was well, shooting about 150 or so shots in AV mode, until I got an aperture "00" and I didn't initially take notice, but I chimped my shots and noticed they were all horribly underexposed. I adjusted some settings to correct this problem, but they were still coming out underexposed. I then noticed the "00" so I dismounted the lens and remounted it. It solved the aperture issue, and all was well.

Several shots later, I began noticing the underexposed images, as well as the flahing 1/8000 shutter speed. I adjusted and changed my settings as much as possible, yet things were not improving. The image were >2 stops underexposed. So I switched lenses to the kit lens, and it continues to underexpose. My buddy looked at it and put it in manual mode, and set things to a setting that should expose correctly, and it did expose correctly, but on the meter reading, it was saying that the photo would be >2 stops over exposed.

I reset all camera settings and custom functions, yet the problem persists. Any suggestions? Is the meter screwed, or is there something I'm missing?

If the meter has failed, has anyone else run upon this problem, and how much was it to repair? I have found nothing in a search on this site regarding the failure of the in-camera meter.

I did a firmware update, I did both the large and small battery reset, and tried several different lenses. Any ideas?

Have you tried to see if the camera meters equivalently whacky in all metering modes...Evaluative, Center, Partial ?

I've had a kit lens fail in a slightly different way. It resurrected three times & then I trashed it.
Have you tried gently cleaning the contacts?

I've tried all metering modes to no avail. I have tried several different lenses, and all are now showing up as having a valid aperture, but all are underexposing severely.

Did you clean the contacts on the camera that connect with the lens? Dirty contacts can cause all of the problems.

I dusted off the AF point screen above the mirror and it seems to have corrected the problem. The "felt" piece hanging down in front of it might have actually been pushed back some causing an issue. Since I had been using a new lens and such a large one, it may have caused that piece to have moved and affected the metering. So far, so good. I will update if this persists.

Tried this?
Need an exposure crutch?