For some reason my browser started to crash when I tried to open documents in Sharepoint. After some investigation I found out that I had multiple versions of an assembly called Owssupp.dll confusing IE. One version from Office 2003 and another from Office 2007. The later one was installed while evaluating Onenote 2007. I solved the problem by uninstalling Onenote 2007. I found a link that describes the problem http://geekswithblogs.net/redwards/archive/2007/06/18/113287.aspx. Additional information can be found here http://support.microsoft.com/kb/833714.