There has been a lot of buzz in the newsgroups about Save As Web hyperlinks not functioning correctly when exporting from Visio 2003 and viewing in Internet Explorer 7. Evidently the problem is only for Visio 2003 and IE7, and when the export uses VML as it’s output.
VML is the Vector Markup Language that enables the rich, vector-based web-export, with all the cool features like Zoom and Search. When Visio exports to html using this format, it structures hyperlinks and sub-links in a way that IE7 doesn’t support.
Two parties that have researched the problem in detail have posted workarounds and tools to address the issue:
Visio Insights: Hyperlink Problem in Internet Explorer 7
The folks over in Redmond on the Microsoft Visio Team have published this article that describes the problem and proposes two work-arounds.
Data Assist: Visio Hyperlink Corrector for IE7 (English) (Deutsch)
The clever guys up in Berlin have created a tool that fixes this problem for you. Have a look!