I have had a few problems with FileMaker Pro 5.5 and a Novell Network drive. I've found that FileMaker really does act funny (crashing, hanging, locking up my Mac OS 9) when I open the files directly off of the Novell Volume.
My solution has been to copy the files to my local hard drive, modify the files and put them back. I am a developer and this works ok for me, but I know it will not work for your situation.
I am currently running FileMaker Server 5 to host all of the my solutions. I host to about 10 instances of FileMaker Pro 5.5. I have not had a problem. But, to help you more, I have also used FileMaker Pro's Remote Data Access Companion Plug-In (Provided with my version of FileMaker Pro 5.5). What this does, essentially, is make my running instance of FileMaker Pro into a mini FileMaker server. Through the Open Remote... command, my users can access the FileMaker files that are open on my 'mini-server.' So I need only one computer to sit there and host the files and all my other computers can access those files concurrently.
With this solution, I have not experienced any problems with changing printers or sorting. I have had a problem when the power plug was kicked out of the computer hosting the files. But, when I brought the files back up, FileMaker automatically performed an integrity check and they worked fine.
Investigate the solution of hosting the files using an instance of FileMaker Pro. This solution will be simple and economical for you.
Best of luck,
damyena