Random Halos in Pictures

[Achickseyeview]

Please bare with me, first time posting. 

I have a Canon 5D Mark ii that has about 57K actuations on it. I am a racetrack photographer and take anywhere betwee 300 - 1500 shots per event I work. After each event, I wipe down all my equiptment and make sure everything is cleaned and covered when I put it away. Recently I've been noticing that there have been these starange halo like lines through some of my pictures. It happens very randomly, and I have tested the camera with 3 different lenses. It's happened with all thre lenses but there seems to be no rhyme or reason for it to happen. I've taken it into a Canon repair shop, and they are just as baffled by it. They suggest that I send it into Canon, however I simply can not afford to send my camera out for 2-3 weeks right in the middle of race season. I'm hoping that someone in here might have an idea what could be happening. 

Note- I did have the repair shop clean the sensor and I will be taking the camera out this evening to see if the issue still occurs. 

Here are some pictures->

[Peter]

Light leak in the shutter. It is not random, it is in a bow. The shutter curtains don't go straight up and down but in a bow and that is what you see.

[ebiggs1]

"I wipe down all my equiptment and make sure everything is cleaned and covered ..."

This may make it look nice but the outside of the camera does not take the picture.

"I've taken it into a Canon repair shop,..."

No you took it to a shop that repairs Canon cameras.  You need to send it to the real deal Canon USA for service because I also believe the shutter is failing. "They suggest that I send it into Canon, ..., and so do I, however, the 5d2 may be out of service life so a call to 1 (800) 652-2666 is your next move.

" I simply can not afford to send my camera out for 2-3 weeks ..."

I know you took offense to Robert's reply but he has a point.  Nobody that relies on his camera for hire or work has just one.  You always need a backup.  Don't you take extra CF cards with you?  An extra battery?  Its no different. That was good advise.