GS748TPS Stacking Errors

I have 4 GS748TPS and 1 GS748TS in a stack, however two of the GS748TPS's seem to cause the stack to have difficulties. It continually reboots the stack and i get very odd error messages in the flash logs on these units.

SOCK-F-SELECT: SOCKP_select_test_socket : Socket id 167772161 is beyond the allowed range
Emergency SYSLOG-F-CORRUPTEDCONTAINER
Aler SYSLOG-A-NONPRINTABLE

(Please note i'm not including the full error as i couldn't seem to post to the forum if i did)

The switches seem to work fine when not in a stack, is this something i'm doing wrong/can be fixed in configuration or are these two units broken and need replacing.

I've not been able to find any information about these errors on the net so i'm assuming they are not very common.

Any help would be appreciated.