"this is probably caused by a security update see http://support.microsoft.com/kb/973904
but before that.. try and rename you .doc file to .docx
an incorrectly renamed file can also cause this error.
if you open teh renamed file and get junk.. then it was probably a binary file and this will not help. rename it back again.
the support article lists this as a possible solution..
Let me fix it myself
To unregister the mswrd632 converter yourself, edit the registry as follows:
Click Start, click Run, type regedit, and then click OK. Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Text Converters\Import\MSWord6.wpc On the Edit menu, click Delete. Click Yes. Exit Registry Editor."