RSLinx Gateway problem

Hello,
I have been having problems with opening a few nodes on our network. Here is my problem...
I can access my PLC5's and one SLC500 on my office PC, (networked) but not 3 other SLC500's. I can access all PLC's and SLC's with my laptop networked through the server. I believe I have configured the topics and drivers the same on both computers.
RSLogix500 responds with "The target node is not an SLC-500 or MicroLogix controller." when trying to access a SLC5/04. Am I having a compatibility problem with different versions of software?
I have RSLinx Classic Gateway (2.50.00.20) running as my server on the plant floor; I have RSLinx lite (2.41.00) running at my office PC; and I have RSLinx Classic lite (2.50.00.02) running on my lap-top.
Thanks for your input in advance.
Eric

hello Eric
I'm a novice at this but if there is a chance the topics and drivers are not exactly the same would it be possible to backup linx on good pc and restore to dodgy pc using RSlinxs backup and restore utility.

cheers