So I have lately been getting the "HTTP Error" on the crunching stage of uploading. I spent a lot of time agonizing over how to fix it, from htaccess hacks to No Flash Upload plugins. I would still get the full-size image in my gallery, but it's dimensions would appear as 0x0 with no thumbnail sizes. After testing for a while, I couldn't find anything to fix it, but I did notice one thing. Small images uploaded with no problem.
Today, this got me to thinking, what is the size that triggers the issue? I first looked at actual file sizes. I tried shrinking my images to 1MB to see if there was a change. Sometimes there was, but other times the problem still persisted. And then I looked in the Multi-site admin options and noticed the dimensions for "Large" size. Hmm, I thought, and decided to try setting my image to those dimensions. What I found was very helpful: an image with both dimensions above the Large setting would crash, but if none or one was below, it seemed to do fine!
I haven't tested this thoroughly yet, but I thought I would let you all know in case anyone else is having the problem, or is stump on where to start for a fix.
I'll take a look at the code to see if I can find any problems soon and report back.