I am using 2 PICs (16f874) on 2 boards to control a system. The board
communicate via SPI with  Fosc/4. The one board switches relays to power
some 220v solenoid valves. Switching the relays on presents no problems but
I can't get them switched off. Removing power obviously does, but  I suspect
the SPI flakes out due to interference from the relays switching on. The SPI
run is about 30cm. My questions are:

1) Should I use a protocol for the SPI and if so, where can I find one that
is reliable and simple?

2) Shielding of the SPI is not an option, how to I eliminate the RFI from
the relays? I have RFI elimination on the DC side, I'm talking about the AC
side

3) Should the SPI lines have termination of some sort?

4) If I halt the SPI on the salve and restart, does it throw away the last
incomplete byte received?

Thanks
Stephan