Time Machine Issues

When I first got Leopard, Time Machine worked flawlessly, but now I'm running into some issues... When I enter time machine I can only access my first backup and my most recent backup. I can see the little tabs on the side for all the backups in between but they are grayed out and I cant click on them... can anyone offer any help?

I found a solution from apple which says the problem could be the name of my computer, but it worked fine before, plus changing the name did nothing to help. I can see all my old backups if i look into my backup drive as I would any other but when using the time machine interface it wont let me access them... Any help would be much appreciated.

Wow... I feel like an idiot... I had excluded the desktop from backups and I was opening Time Machine with no open windows so it was opening in the desktop, for which no backup except for my original backup. If i hit the applications folder i could then access all of my backups. If anyone else has this issue, I hope this helps