script errors showing only with ie8 and iis7

Question

I have recently move a website from a server running win server 2003/iis6 to a new server running win server 2008/iis7. When I browse to the new site in ie8 I get javascript errors:

Object doesn't support this property or method

And

Sys.ArgumentException does not derive from Sys.Component

These errors go away if I:

-Switch to compaibility mode -Browse with ie7 -Browse with FF -Browse to my old site (iis6 win server 2003) with any browser.

The page uses Telerik controls. The master page also brings in the MS script manager

Answer 1

It might be fixed in the latest version of the Telerik controls, since they've talked about such a problem with the IE8 beta in their forum, and promised a fix, which should have arrived sometime in April:
http://www.telerik.com/community/forums/aspnet-ajax/form-decorator/form-decorator-amp-ie-8-beta.aspx

Answer 2

Are you sure that you are browsing the old site with IE 8 NOT in compatibility mode? If yes, then you can try switching the new site to IIS 7's Classic App Pool, which should make it behave quite similar to IIS 6.