I've had a similar problem in V6I in XP (just had one case yesterday). I also do frequent "save as" and sometimes, when it gets big, a file just refuses to open again (it stays loading indefinitely). I contacted e-on support the first time this happened (a few months ago) but they couldn't help. I don't have any solution, so if you find one, I would be very grateful. Thanks!

EDIT: oh, and by the way, I have no hibernation nor standby mode activated, so it's not that, at least not for my case.