Index was outside the bounds of the array ver 1.8

Hi there, brand new install at http://yarnnecklaces.noptm.com, click on a category and see what happens... Help?

Looks like it happens when you add a "price range" in the category and leave out the - or not 2 numbers: example:

6.95 produces the error, 6.95-10.95 does not...

Code may need to "look" for that? I made the mistake and only added 6.95, it bombed it...