MS Office update disables some MS files
Microsoft's Service Pack 3 for MS Office, released in December, blocks the opening of some older format office files.
The service pack will block access to some files including those created using Excel 2003, PowerPoint 2003 and Word 2003, as well as Corel Draw formats. Microsoft said: "By default, these file formats are blocked because they are less secure. They may pose a risk to you."
We haven't been able to establish what the risk is, or why they were not previously regarded as a risk. Presumably, if it is a file you created yourself then it should be okay to open it, but if it is a file sent to you by someone else then it may contain malicious code. However, our understanding is that the patch does not offer you a choice of opening the older files, but simply refuses to open it. Microsoft has provided a workaround for users who need to access such files and there is more from Microsoft here:
support.microsoft.com/kb/938810/en-us
18th February 2008