I have two Windows 7 machines connected to a router. I created a shared folder on machine A, and I can access it from machine B. The transfer speed is great.

However, there is sometimes a long initial delay when I try to access the shared folder from machine B. I'll click to open the folder, and windows explorer pauses for a few minutes before actually loading the contents of the folder. After it loads, however, I can navigate the subfolders and edit files with no noticeable delay. Then, some time later, I will get the huge delay on saving a file, after which subsequent saves have no delay.

What is the problem here, and how can I fix it?