Search and post functions returning IE errors...object undefined, ajax..

My colleague searches in search widget (main search box on community home page) on something he knows we have in topics, but search retrieves nothing and sends to create new topic page, and then topic doesn't post and errors occur. Any ideas?
IE version 7.0.5730.11

I couldn't post pics (TypeError: 'responseText' is null or not an object) http://www.getsatisfaction.com/getsat... will forward pics in email.

errors include things like:

line 1214, char 1, object doesn't support this property or method, on /positscience/topics/new?/topic%

and

line 948, char 1, ajax is not defined, on /positscience

He also can't post in the get satisfaction support site.