That sux. Only thing I can suggest is to save the file as a GPX and then open it into an editor to look at the data. There are a bunch of freeware GPX editors out there.

If your bike is in a safe location, just leave your computer on, but make sure "autopause" is enabled. I'm pretty sure it won't power down in that mode, but would have to check the manual to make sure.

Can you send your FIT file to Garmin and ask them what's up?