Anyone know how to fix this error? Race condition

[bfdzio]

Ok so last night I got reports from users with 1 particular thread causing problems giving them a 500 error. I checked the logs and this is what I got:

[Tue Apr 25 08:05:30.088781 2017] [core:error] [pid 27436:tid 139842581161728] [client 198.47.254.41:59955] Caught race condition abuser. attacker: 500, victim: 99 open file owner: 99, open file: /home/nciu/public_html/forum/clientscript/vbulletin_css/style00032l/dbtech_thanks.css, referer:

Now, I have tried all the maintaince stuff and also turned off storing stylesheets as files. Not sure what else to do? It seems to be an issue with permissions but it all goes back to the css files. I have made sure the permissions are good on all of them but also have turned off storing as files and still get the same result.

Any ideas?