My forum might have been hacked

Hi, I've been looking around for an answer but haven't found one. I took over a forum not long ago, and I'm new to the whole admin thing, but an old member of the forum (one who hasn't logged in for a long time) posted and said somebody from my site hackd his account. We're using vBulletin from 2006 (I know, it should be updated). Is this common? Any ideas on how to prevent it?

 

What's your url?

 

If you have SSH access/VPS or dedicated server might want to read http://www.vbulletin.com/forum/blog...in-forums-for-vps-dedicated-hosting-ssh-users which basically is a small excerpt of the much larger 10 page guide ?http://vbtechsupport.com/2355/.

 

I sorted it out, thanks for the input. Seems there was no hacking but the member who came back with that story was full of shit.