File associations

I had a virus, kak.htm, which was removed, but one of the files was help.hta in the Windows directory, and after this file was removed, the file associations window (Open with …)popped up, not once, but many times.
So I linked help.hta to Excel, now its even worse, as Excel takes longer to load, before it says it can’t load it. How do I get rid of this? There are no help.hta or *.hta files in the system and no references to them in the registry or startup folder.