What would that be ?

I am really interested to know. Right now I am running EXT4 on an SSD in my notebook. It performs well. Sometimes, after a suspend , I get a load of EXT4 error messages which are stalling the whole notebook. Hard resseting it, makes the error disappear. Up to now, no data loss.But anyway, this makes me a nervous and I am not sure if it is due to Kernel, SSD, Ext4 or the combination of all/any of them. I guess XFS is way out of my use point, but anyway, an option is an option.