I hope this is a stupid question, and not the beginning of a protracted battle against an unknown beast 
So... two of years ago I toyed with the cheap MCP2515 CAN board (the one with the 8 mHz crystal and the JA1050) and Cory Fowler's library), and I was able to connect successfully to the module using an Arduino 2560 and the "Receive" example. Life happened an the whole thing was stopped and the protoboard used for other purposes (--> wiring removed).
Yesterday I tried to go back to the code using the same components and same example. I redid the wiring using the diagrams found elsewhere in this forum and on the web (e.g. instructables, changing the pins for the 2560, of course), but this time all I get on the serial monitor is an error:
Entering Configuration Mode Failure...
Error Initializing MCP2515...
MCP2515 Library CAN_Receive Example...
I tried with different arduinos (Leonardo, Mega 2560) and two different MCP modules (including one fresh out of it's anti-static bag) but I keep getting the same results.
I triple-checked the connections, re-did the wiring, and reinstalled everything, yet the result is still the same.
So... is there anything besides the boards and the library I should be checking? Is there any known incompatibility between a certain Arduino IDE and the MCP_CAN_LIB?
Thanks!
[Edit] The problem ended up being the serial port on the Leonardo. I replaced it with still another Uno and seems to be Ok.