Flex Net Noise: Any Ideas?

Yes, it's likely to be something quite nearby you.  The thing to do is to start switching off your AC circuit breakers one by one (excluding your shack!) until the noise stops, then track down the devices you have plugged into that circuit.  It looks like a cheap switched power supply - or wall wart.

73 Martin AA6E

One way to check is to zoom out on your display to show more screen bandwidth.  If you see those same noise spikes evenly spaced multiple times.  That is a good indication of switching power supply interference.  Wall warts are basically switching power supplies.  Using #75 and/or #31 ferrite on output and/or input can lower the emissions.  Or do like I did and use an appropriate new supply of better quality.  I use a small Meanwell product like 5v or 12v power supplies and I common up all the devices needing appropriate voltage supply.  Reduces number of wall worts and I do some some #31 ferrite to reducing Ingres of RF from station transmitter.  This method reduced the **** by a large margin.  

Use the power of the radios built in spectrum analyzer to help trouble shooting interference problems.