I have been solo mining since June 2016. Like clockwork, I receive Gridcoins every 2 weeks from multiple sources.
I received my last coins on 28 October 2016. Since then, for all 11 BOINC projects that I run, I am getting the message, "INTEREST 218 days Searching for coins INVALID CPID"
In Gridcoin, under Advanced, I run Diagnostics, and Gridcoin tells me that everything "passed".