I've seen this issue talked about on several other forums but just had this happen to me last night during a performance and am looking for answers.

Using a 5d Mkiii, shooting to a SanDisk Extreme 45 mb/s 32 GB card, and using a 24-70 2.8L. It was about 4 minutes after I hit record. Battery was at maybe 75%, card was not even half full. Maybe 25% at the most. The camera froze & I had to remove the battery to reset and start recording again, and I lost my file.

Hoping this is an issue that has been or will be solved through a firmware update? Anyone else experience this?

Even though I use only Hoodman cards (the peace of mind is worth the extra price, to me), I format before each shoot. I don't trust the cards once they've been in my computer. Knock on wood, I've never had any issue like you describe.