changing configuration of clients

Hi there
I have an unusual problem. In my previous job I configured and maintained a farm (8 render clients running XP Pro x64 SP2 and Dispatcher running Server 2003) for Maya 2009 using Muster 5.5.7.
My current company aquired this farm and I have reconfigured it successfully for Maya 2011 and it was working fine. Someone asked me to rename the server and I did so without thinking. Obviously the license stopped working so I changed the server back to its previous name and the license was OK again. However, since then, two of the render clients can’t find any network maps on the server. I have tried both the boot drive and the RAID we use for project storage. The Muster Explorer shows the instances as idle and ready, but as soon as a job is submitted the instances on the affected clients return an error ‘Chunk 1 belonging to job test processed by host Render 08[1] returned the following error: Unable to map drive P: to \Pc-serverProjects’ or whatever map letter/pathway I hav also tried. All the configs are the same as far as I can see with the exeption that when I run rundll32.exe keymgr.dll, KRShowKeyMgr, the Stored User Names and Passwords dialogue box on the good machines are empty and the same dialogues on the bad machines have the server administrator login saved. Deleting this causes the server drives not to be available in workgroup computers when I try to remap the server drives. Can you give me some guidance please, as I’m scratching my head here and out of ideas.
Thanks
Chris