I realise that this is a very similar issue to https://tracker.moodle.org/browse/MDLSITE-2373 but I don't understand caching well enough to debug my own issue or to be able to following the debugging instructions in that ticket. I would be really grateful if someone could tell me where to start looking. We are on moodle 2.4.6 and I'm seeing the following in the apache error log:

Default exception handler: Coding error detected, it must be fixed by a programmer:
Failed to unserialise data from file. Either failed to read, or failed to write. Debug: \nError code: codingerror\n*
line 468 of /cache/stores/file/lib.php: coding_exception thrown\n*
line 371 of /cache/stores/file/lib.php: call to cachestore_file->prep_data_after_read()\n*
line 295 of /cache/classes/loaders.php: call to cachestore_file->get()\n*
line 1358 of /cache/classes/loaders.php: call to cache->get()\n*
line 322 of /cache/classes/loaders.php: call to cache_application->get()\n*
line 1358 of /cache/classes/loaders.php: call to cache->get()\n*
line 6547 of /lib/moodlelib.php: call to cache_application->get()\n*
line 6696 of /lib/moodlelib.php: call to core_string_manager->load_component_strings()\n*
line 7423 of /lib/moodlelib.php: call to core_string_manager->get_string()\n*
line 1240 of /course/lib.php: call to get_string()\n*
line 871 of /lib/modinfolib.php: call to get_module_types_names()\n*
line 754 of /lib/modinfolib.php: call to cm_info->get_module_type_name()\n*
line 48 of /blocks/activity_modules/block_activity_modules.php: call to cm_info->__get()\n*
line 764 of /blocks/moodleblock.class.php: call to block_activity_modules->get_content()\n*
line 232 of /blocks/moodleblock.class.php: call to block_list->formatted_contents()\n*
line 953 of /lib/blocklib.php: call to block_base->get_content_for_output()\n*
line 1005 of /lib/blocklib.php: call to block_manager->create_block_contents()\n*
line 353 of /lib/blocklib.php: call to block_manager->ensure_content_created()\n*
line 7 of /theme/ucl/layout/course.php: call to block_manager->region_has_content()\n*
line 810 of /lib/outputrenderers.php: call to include()\n*
line 740 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()\n*
line 243 of /course/view.php: call to core_renderer->header()\n,

We have 3 load balanced application servers and a separate server for the data which is loaded via an nfs mount. The errors occur intermittently and I've been unable to replicate. When the error occurs the browser displays:
"Coding error detected, it must be fixed by a programmer"
but on refreshing the browse the error disappears. I don't know whether this is a bug in core code or a problem with out configuration.
Many thanks in advance