I have a microsoft office live site and recently my unique traffic has dropped. I noticed that the metatag keywords and description I'd posted in the appropriate place had been deleted - could this explain the drop in unique visitor numbers? Now I've replaced them, how long will it take to have an effect?
It's hard to say what caused the drop, but it's quite common that it happens once in a while. So it might not be something you did to you sites, just that some other sites got bumped up for something they might have done.
There are many problems with Office Live and they limit your ability to optimize your SEO. I used them for a while but they had so many limits that I just switched to another host. If you are using their free service, when you cancel your account you can transfer the domain name to another registrar for free (just the cost of adding a year through the new registrar). That is what I did and was much happier with more control.
rankings change all the time and I doubt meta tags are the reason for your drop....put them back and just be patient....