You failed to specify operating system or network.
BUT, since you said ‘change location for the save’ I am guessing windows on a network. And your problem is not uncommon. There is an unreachable resource. When you do ‘Save As’ and try to change location, ‘Windows’ tries to verify (access) every local and network share to build the list you ask for. Any server that had been mapped and is now offline, any network printer that is now offline, and peer2peer share if you are in a workgroup, not domain, and any FTP site that you saved as a network place. You imply that this is the only system having this problem. Check network places, printers, mapped drives, network shares, and ‘Hosts/LMHosts’ files. If it hangs when trying to open ‘My Computer’ or Windows Explorer try ‘safe boot’ and various local folders. Good Luck.