Frames fading when i am working on my project but non of the settings have changed

[Shighguard]

So I have been having a random problem with animate the last couple days. Some of my frames/layers will randomly change transparence. Suddenly one of my characters heads will be nearly invisible but if i go back a few frames and then back to the frame i was orignally on its fine. Or my background will suddenly disappear, I have no idea what is happening. Non of the settings have changed, alpha levels are still the same and the problem fixes its self shortly and if i test my movie it doesnt change anything there. It seems to be more just an annoyance then anything but I just want to make sure this isnt part of a larger problem that will ruin my project. 

Thanks for any help

[n. tilcheff]

Always save copies of your file with increasing version number several times a day.

Always keep backups on at least two external drives.

This may be a sign of running out of memory, a problem with your system or a rare bug in Animate.

Never rely on the auto-recovery option.

[_keyframer]

Sounds like you have Onionskin on?