Curious problem – I kept getting an error message “Internet Explorer has encountered a problem and needs to close. We are sorry for the inconvenience.” whenever I tried to open a document from our internal MOSS system. Strange.
We use Project 2003 still. This means two version of the owssupp.dll, apparently, under c:program filesMicrosoft Officeoffice11 and office12
I followed the advice from the MS Knowledgebase article, but got the same error as all the folks at kbAlertz. In the end I tried just uninstalling MS Project Professional 2003 support – and low, Internet Explorer started letting me open documents from MOSS again. And, much to my surprise, Project 2003 web access works just fine – I guess it doesn’t use that dll.