This happened to me after I removed (uninstalled) Adobe Creative Suite 2. This problem has already been reported by Adobe TechNote Website under the titled ‘File system, I/O, Illegal Name errors, or system crash after you install (Photoshop CS2, Illustrator CS2, Adobe Creative Suite 2)‘.
The solution it suggests is to use the Disk Utility to repair the disk, which I have already attempted with NO luck. The error produced by the Disk Utility is as follows:
Disk Utility reports: First Aid failed.
Disk Utility stopped verifying “The name of your disk volume” because the following error was encountered:
The underlying task reported failure on exit.
and the illegal name being the ONLY error listed.
Then I found another way of removing these nasty illegally-named folders and files by the following steps:
1. Reboot the OS X and during the start-up, press and hold both 'Command' and 's' keys, this will boot your Mac into the 'single-user mode '.
2. Then you will be presented with a terminal-like environment, then type 'fsck -f'.
note: (fsck: filesystem consistency check and interactive repair)
3. When fsck finishes, type 'reboot' to restart your Mac.