Windows 7 Work net work problem

[K Daly]

I have connected to a work network, no problem. I mapped the drive and can see and access all files but if I make a change and try to save a file I get the message file can not be saved. It then changes the file to a temp file that can not be opened and in effect loses the file. What can be done?

Server: Windows 2000 Server
Other Computers: XP Pro
Wireless Router Llinksys