Excel attachments trying to open a .php file

Hi,

I have Mac OS X 10.4

I subscribe to two other vBulletin forums and am having problems opening file attachments.

On one forum, all the Excel zipped attachments open perfectly. However on the other forum all the attached zip files I've tried, (about 20), try and open with something called a .php file type which means nothing to Excel. Funnily enough I did find just one file this afternoon on this second forum which did open OK.

Most of the users of the forums clearly use PCs with Windows, and I had first put this Excel unzipping problem down to the fact that I am using a Mac. However the evidence so far suggests it might be something else, particularly since I have no problem opening zipped Excel files from one of the forums.

Has anyone any idea wherein lies the problem, and how I can get round it?

Regards.