On certain occasions I've had problems that I've solved by a shotgun approach of taking the interface down, unloading the module, reloading it, and reconfiguring the interface.
Not sure which of these steps are the necessary ones, but it always works.
Also I'm using the rtl8139 module, not 8139too (Donald Becker seems to think more highly of it
)
Also normally "says something about" is not the kind of detailed error reporting that gets problems solved quickly.