Otaku Legend | Posted 01/12/11 | Reply
Thats fine! I should probably start saving my linearts anyway ;o;
I'm sorry, but I don't have any experience with SAI, but it sounds like something that my art programs do to m every once in awhile.
I don't remember what I did to fix it, but I think I just saved the picture and opened it up again.
If that doesn't work, I'm sorry I couldn't be of anymore help :C
It also helps that while you're doing a picture, you save the line art seperately and/or save a copy of the current picture periodically in the format of your art program, so that your layers stay put.