Were you able to resolve your issue? I ask because I am in the same situation. I did not backup my files as often as I should and I hadn't backed up in over a year though I thought I had set it to autobackup.
Anyhow, my most recent Family Tree Maker 2010 file is 54.1 MB and will not open. It asks to compact the file and yet when I try to open the file to compact it doesn't open and an "unable to compact" file pops up. I have updated my Windows and my FTM 2010 file is up-to-date too. I have uninstalled the program and re-installed it (I still had the disk) with no luck. My older back ups show up fine. I even made a "new" tree to see if it was the program, but the new tree did not crash so I think it is something with my file.
I am at a loss--3 years of work. I want it back and once I do, I plan on taking advantage of the mitigation utility so I can move it to a Mac since I am unimpressed with PCs and, I will back up often.
Anyhow, how did you open your large file and resolve the issue??