I'm assuming you are writing about McMaster-Carr.
I've never run into your issue using IE or FF.
Now if you are super fast, you might look like a bot to mcmaster. There are places that harvest McMaster to come up with cross reference part numbers so they can sell you something close. Perhaps McMaster is fighting back.
McMaster is the most awesome hardware site on the planet.
Wes
-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller