If you put the files on the other mac, do they open remotely on the other mac?
There is a possiblity that the Directory is subtly damaged or massively fragmented, DiskWarrior is the best bet ($100 - Alsoft)
SuperDuper Boot copy to external drive, erase original, copy back will likely fix Directory and Fragmentation.
There is a possiblity that the database is massively fragmented - copying to another drive (external) and testing would give a hint. iDefrag is a best choice for defragmenting.
Possible the hard drive on the original mac is failing (unreliable sectors) copying to another drive might show this.
Ram insufficient on original host - Activity Monitor in Utilities in Applications can be set to Keep in Dock and show System Memory (Pie Chart), you may need more RAM - this is the most likely single cause, but there could be three things acting together.
I assume you are HOSTING and not using FMP Servers and, also that you are on a local net and not using the Internet.
One other question...
Are you ethernet wired connection and Wireless?
I have experienced the need to Force Quit when,
1) accessing a DB with many pictures or PDF files that are sorting on the Start Up script. [Very Large files]
2) When the previous user was disconnected abruptly or power outage.
3) Accessing the HOST computer that has the Energy Saver setting that was putting it in a total power down mode.
4) Local net traffic was high use.
LOL, I was entering my comments at same time as DavidAnders and didn't see his. His comments trigger some other possiblilities.
What is Mac A age and clock speed? Mac B? Did you know that even though MacOS has been 64 bit for many years, they didn't fully utilize it and that older machines with 10.8.2 run remarkably slower than in 10.7.5?
With the advent of 10.8.2 it is almost impossible to have hard drive problem that the OS doesn't pick up and repair. I use Tech Tool Pro and it does the best testing and includes a Network check also.
Jim, David, we solved it, with a bizarre solution - if we daisy-chain a crappy old Netgear router into the equation, all is well. So:
• instead of Comcast Cable > Comcast modem > split into four signals (3 computers and a printer)
• we use only one port on Comcast modem, and run Comcast Cable > Comcast modem > Netgear router > split into four signals (3 computers and a printer)
Now, why every other bit of networking worked with the first configuration (internet, all file sharing EXCEPT certain FileMaker databases) baffles me. Thank you for your responses.
Did you know there are network collisions using wireless and wired from a Mac? Although rare! Sound like the "crappy" one is Comcast. If you read about the FMP port use, it is not hard to invision a network error on a massive FMP file.
PS: If i am wired, I turn off AirPort.
Have you looked at the File - Manage - Data sources? It could be there are lists of data sources in there which the remote computer is running through to test for a connection. If all the files are local then it can run through quicker, or it could be that the locally-available file is higher up the list.
I second that. The amount of time FileMaker can take to determine that a particular external data source file reference is not available, can be HUGE.