This is a Kyocera CS 3051ci multi-function network printer, connected via ethernet to the router. The "server" in question is actually just a Windows 7 Home Premium functioning as the "server" in the office.

First thing up, ALL functions, including the scanner function, work perfectly. Scanning saves the document to any of a variety of folders on the server, depending on who is doing the scanning. The destination addresses are chosen from a menu each time. Sooo... after the "server" has been up and operating for 15-20 minutes, the scan function begins to fail with the "Failed to send via SMB" error message. When this happens, it happens regardless of the destination chosen. ALL other functions of the multi-function printer: printing, faxing, etc. continue to function flawlessly. It's ONLY the "scan" function failing. To correct this error, all that is required is to reboot the server, then it works correctly again for 15-20 minutes.

What is happening to cause this error, and where do I begin looking for the solution? Nothing obvious appears to be mis-configured, as evidenced by the fact that it works fine for awhile after the server boots up. I'm pretty confused by this one...