Unable to open microsoft files from links

I have several machines that are unable to open files from links/attachments, it appears to only have the problem with Word/Excel/Web links as PDF and PowerPoint appear to open correctly (although possibly a bit slow).

For example if I receive an Excel attachment if I try to open it directly from the attachment, Excel opens, however the spreadsheet itself never opens. If Excel is already open when I attempt to open the document, it will then open the document. It does the same thing for Word where it opens word but not the document, unless word is already open.

When you click a web link, it does not even open Internet Explorer, however if you have IE open when you click the link, it will open the page in a new tab.

Both machines are running Win 7 Enterprise x64, as far as I am aware no software has been installed or uninstalled within the last few weeks.

I have been searching around the web for solutions to this problem and so far nothing I have found has corrected the issue. I have reset IE settings back to default, made sure that excel is not set to ignore other programs that use DDE, double checked the registry keys under HKEY_CURRENT_USER/SOFTWARE/CLASSES are correct ... I am out of ideas and any help would be greatly appreciated.