Please Help - Can't get into my admin's categories/products area

Hi. I have been using zencart with No problems for a couple of months now. Currently, I can access everything in my store but one area - the categories/products area. I cannot get any of my individual products to open from the admin side. As for my forum, I cannot get in to add posts and some of the forum will not open for me...and I am the site administrator. I have checked with the individual that created my store and everything runs fine on her end so this is only happening on MY computers. I have NO deep computer knowledge. If you can help me or know of someone who can Please email me directly at [email protected]. Your time and help is greatly appreciated!

Thank You!

Melissa