1 person found this helpful
...sent to me...
File corrupted in transmission, I'd bet.
Have your colleague put the .ai file in a .zip archive before transmitting it to you.
It has to do with resource forks in the Mac filesystem (_MACOSX, ._DSSTORE, etc.). If a file is not zipped, this information does not travel with the file. So, zipping the file solves it, but not for the exact reason stated. I marked your answer as helpful though since it did mention the solution.
If a file is not zipped, this information does not travel with the file.
There are many mechanisms in place -- e.g., MacBinary, AppleDouble, BinHex -- that deal with this issue, and much depends on the e-mail client in use. Other than fonts and executables, resource fork data are largely irrelevant, especially since the change to OS X.
I routinely move files (including .ai) between Windows and Mac OS systems across a network, and all I ever have to deal with is the data fork on HFS+ files. The file "corruption" to which I referred need not be something attributable to the "ether" but, equally possible, to file handling by e-mail client software.