when i try to open a file, i'm getting this error...

"There was a problem reading the layer data. Read the composite data instead?"

was reading some posts and saw that people were sometimes getting this because they were working on the file over the network. the file i'm trying to open is local on my machine. is there anyway to repair this or am i basicall SOL. the file size is about 250mb. also, what causes this so i can try to make sure it doesn't happen again when i recreate the file... if i have to.

specs from my g4 -

os: osx panther
machine: g4 867 MHz w/ 1.5 gig of ram
ps: cs