Thank you for your post, and I apologize for the late reply.
I am unable to replicate the problem. On my iMac running Mac OS X 10.7.2, I launched FileMaker Pro 10.0v3, created a database file with a Container field. In the first record, I selected Insert Picture and selected a file from my local drive. In the second record, I inserted a picture from a mounted server. In the third record, I inserted the original picture, and in the fourth record, I inserted the picture from the mounted server. Each of these files are TIF files. I then repeated the steps with JPG files.
I know three months have passed, so if you have found a resolution to this problem, please post it here so others with similar symptoms can benefit.