CSS Style sheet doesn't load

I'm not sure if this is even a vBSEO issue or not but I seem to get more help here than on any other site.

So anyway, this has happened a few times in the past but if you were to reload the page the css would load so I just left it be without looking much into it. Now I have a user that can't load our CSS stylesheet...ever.

I wanted to see if anyone knew what could be causing this or has a solution to this problem. The thread the user made is here:
Se7enSins Glitching Forums

And here's the screen shot the user took:

I doubt that this is a vbseo glitch especially since it only happens for one user. What happens if he tries a different web browser?

It has happened to many users, counting myself. There's no specific browser either. It's happened to me using both FF and IE. This individual is using firefox. He is the only unfortunate one that can't load the css ever. People will get this on one or 2 pages and refresh and it will be ok.

This has happened on previous skins but not to this extent. He can load the default skin though...that's what I'm getting confused by. Everything seems to be coded fine in the headerinclude and header...so I can't figure out what the problem is.

He has no FF addons, no security programs that could be blocking something...and he's using FF which usually is great for websites...so I'm at a stand still and I'm hoping someone could help me figure this out.

I'm using eAccelerator. Would that have the same effect?

Quite possibly.

Next time it happens, check the source of the page and see what the link to the css sheet says. If this is the issue, it will be an older css stylesheet referenced in the source.

My sysadmin says the cache is cleared every five minutes.

And I think I've looked at the source before when this has happened to me and it doesn't even link to the css stylesheet...