Here is what I found:
Error Message
%AAAA-3-DROPACCTLOWMEM : accounting record dropped due to low memory: [chars]-[chars] [chars] [chars]
Explanation An accounting record has been dropped because of low memory.
Recommended Action Disable periodic accounting if it is activated. Reduce other system activity to ease memory demands. If conditions warrant, upgrade to a larger memory configuration.
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Are you running any additional services on the affected switches that aren't running on the good switches ?
Having the same IOS in all similar hardware is considered best practice, I recommend doing so.