So, IE sucks. The javascript errors usually look like:

Line: 1
Char: 1
Error: Object doesn’t support this property or method
Code: 0
URL: http://art.renoir.brylanehome.com

Which could mean absolutely anything at all.

Anyway, here’s the solution: debugging JavaScript with Visual Web Developer Express
They’ll walk you through setup, and from there you can get some actual debugging done. It’ll show you what line of code actually caused the error and it’ll give you real messages rather than a blanket one. It’s free too, but that’s expected.

Of course, normal people just use Firebug in Firefox.