Errors with Cisco Nexus switch

We have a customer using multiple units containing Connectcore 9215 and ME9210 modules; all satisfactory so far. Software is Net+O/S 7.5, generally no more than 2 years old.
They are now moving to Cisco Nexus switches, and have encountered problems talking to all our products (among others). Network traffic is generally not demanding; probably 20 messages per second at most, and often much less.
Typical symptoms are that after 10-15 minutes of error-free operation, the unit becomes inaccessible. It recovers after about 20 seconds. The process repeats at intervals, then reaches a point where our unit locks up completely, requiring a power cycle to reset.
Has anyone else seen similar problems?

Are you able to reproduce this on a module with JTAG? if so, when you reproduce it pause the execution and look at the call stack. Is auto-negotiation enabled on the switch? If not and there is a duplex mismatch the ethernet will stall.