Thank you for your post, and I apologize for the late reply.
Can you tell me more about the files being accessed? Specifically, are the files hosted on FileMaker Server or FileMaker Pro? Are you accessing over VPN? Any other information you can provide about your computing environment will give me a good place to start.
I know three months have passed, so if you have since found a resolution, please post here so others who have a similar issue can benefit.