Errors in log point to network issue?

[mpprevost]

So we've been having some issues at one location as far as connectivity to outlook is concerned after we upgraded to exchange 2016. The exchange admin pointed fingers at the network, the network admin couldn't find anything wrong except outlook. However, looking through the controller for that building it may point to some other issues and I can't find anything about it online and my vendor has never seen the errors before. Has anybody seen this error before? If so, what does it mean?

Log Type   Log Number   Severity   Date   Time   Source                  Description                                        Module                                   File Name and Line Number
Software   4915           Warning   2016/Feb/26   8:15:07   IP Networking - MIPS   arl_write 01:00:5e:00:00:fd(0001) error -1   Main   MIPSServiceProvider.cpp;1062

[lundah]

Looks like it's indicating an issue writing something to a MAC address, but that MAC address range is reserved for multicast traffic, which I have no idea why a 3300 would be sending. What version chassis is it? There's certain vintages of the MXE-II (part numbers 50005090 and 50006211, specifically) that are known for having issues with the MIPS processor (runs the onboard L2 switch), maybe this is pointing to an issue with that?