I've got two 5,1 Mac Pros that both are suffering from daily issues with Finder locking up and locking up on shut down (even when shutting down during stable period). One machine connects to a server using AFP for most work, and the other only uses internal drives. For the most part they share little similarities in use patterns, and yet both are suffering same problems. One is a 12-core with 16GB OEM memory & dual 5770s. The other is a 6-core with 12gb and 5870. Both have all available updates installed. Have others with 5,1 and lower Mac Pros been experiencing these 10.10.3 stability issues? Any resolution aside from down grading? Our two nMP models seem to be operating fine, so I'm biased to think the stability affects the older models more.