error -36 I/O Error, sounds generic, but is actually very specific.
It says that even after re-reading 1,000 times using error correction, some blocks would not 'come clean' and their contents are unknowable.
When deleting data files, errors in the data blocks are not that serious -- they are being discarded after all.
But errors in the Directory blocks could mean that the sizes and locations of files are the part that is unknowable -- and that is serious.
I recommend you launch Disk Utility and attempt to FirstAid/RepairDisk on the boot volume.
If no joy, you may have to use Recovery for this.
post back if you need more explicit directions