Ok, so I think we finally have this sorted out. The client called Centurylink who tested her line and found it faulty. She did order a replacement modem, though they wanted to charge her $100 for it. Anyway, the tech comes out and finds the problem with the line and fixes it. He then tests the modem and says it's fine. She calls and I remote in, and sure enough the modem is working as it should. This saves her $100 and she's happy. I remote in again later (just to check) and everything is still working fine. I then repair the SPP errors using the method your suggested in your link above, and everything looks to be resolved. She's happy that a problem she didn't know about is resolved and didn't cost her anything. Thanks for the help!
