I have a user that runs Windows XP SP3 with Office 2007 installed. Somehow he can't open any files with .xlsx extentions (as attachements in Outlook or after he saves them to the disk) which is already quite weird... When I go to Folder Options / File Types - there is no program associated with this extentions and I'm not able to add it - every time I browse to where EXCEL executable is located and click Open, Excel won't appear in the list of the programs to choose from... so i can't add it. Ridiculously, when I login as a different user - everything works - i tried 3 different user accounts. I added the problematic user account to the admins group - didn't help. I uninstalled Office, did the registry cleanup, run CCCleaner, and installed Office from scratch a couple of times - still the same problem. Looks like this issue is related to a particular user only... Any input will be greatly appreciated!