Hot pixels at high ISO & frozen camera?

[Glen Elliott]

Now that I've gotten a good amount of all dslr weddings under my belt I've noticed something and also have encountered a problem. I'm wondering if the group might be able to help me out.

HOT PIXELS AT HIGH ISO:
First off, as I explained in a post in winter, I notice a hot pixel in all of my 7D footage when shooting at a high ISO. When the ISO is low or the camera is cool (i.e. just turned on) it's not an issue.

Until yesterday I thought this was an issue plaguing only my 7Ds. Well apparently it's true with my 5Ds as well. I noticed it more because I used a 24-70 2.8 instead of my normal 24 1.4 for dancing at the reception. The slower 2.8 f-stop required more gain than usual- occasionally teetering towards 3200 ISO. In this footage I have a red pixel, or in some extended scenes looks like a grouping of pixels in the lower right of the frame. As soon as I swapped to my 24 1.4 and lowered the ISO the dot got much less visible. As soon as I shoot in better light with lower iso (say, under 800) it's gone.

My questions are:
1. Does everyone encounter this with their cameras (5D and 7D in particular)? Again I thought my 5Ds were invulnerable to this phenomena however apparently high ISO will still make a pixel on the sensor glow.
2. I hear about people sending their cameras in to get dead/stuck pixels fixed is this what they saw which prompted them to send it in? Or was it something worse where the hot pixel was visible even at 0-200 ISO?



FREEZING CAM
A few weeks ago at a wedding ceremony my wife moved the tripod during the precessional and the camera froze and came up with some sort of error message stating something to the fact about not being able to read the card. Unfortunately I didn't get to see it and she was obviously flustered due to the untimely manner of this glitch. She quickly replaced the card and continued shooting.

When we got back and started unloading the cards the first file was on the card but the one that it had given her the error message was completely gone as if it was never shot. I used Card Rescue to see if it was there but not visible due to corruption and to no avail. The file was simply not there.

I figure that maybe she bumped the camera too hard when she put the tripod down. I know this can cause a drop-out in tape cameras.

Fast forward to yesterday. I'm filming a catholic ceremony and get to the end of the ceremony where I frame up my camera and leave it unmanned to grab the glidecam and prepare for the recessional shot. When I get back to the unmanned camera it had frozen. No error messages, just a frozen screen with the last record time listed as 8 minutes and few seconds. I try to turn the camera off and it wont turn off. The only way to get it to unfreeze was to eject the battery.

When I put the battery back in and power up the camera and check the card. The last file is missing. Now I'm not sure if this was a camera issue or a card issue....or possibly caused by another "bump". The camera was indeed placed close to the pews in the outer aisle. When guests were exiting they may have bumped it but I have no idea.

I'm not sure how to go about figuring out the issue. It's not something that happens often. If it were it would be cut-n-dry. However I worry if i send in the camera to Canon they'll send it back explaining that they couldn't reproduce the problem.

I'm also not ruling out a card issue. As this was the same card that was in use when she got the error message (albeit a bit differently- at least it didn't completely freeze).

Has anyone encountered something similar with their DSLRs? If so how did you zero in on the culprit?

Thank you in advance!!!!