The rightmost LED is the Error light. How fast is it flashing?
If the light is flashing 1 long flash every 4 seconds (no other lights flashing), then either the image drum needs to be changed or the toner is low.
If the flash is one blink a second, then you have a paper problem or a cover open.
If you installed the OKI software with the driver, you can use the Printer Status monitor to identify the problem and order the consumables if you have a slow blink error. (Open the printer control panel (Start >Programs > Status monitor) and Maximize the window to see the Printer status.
You can find the manual for the OKI B4100 here:
http://my.okidata.com/PP-B4100.nsf?opendatabase . View all manuals on the right. If that link doesn't work, see the support site:
http://my.okidata.com/Home.nsf/Welcome?OpenFrameSet and select the B4100 in the Color/Mono Page Printer drop down menu.
I hope this helps.
Cindy Wells