quicktime player error during internet downloads

[rmcbird]

HELP! I can't download any program from the net. Anytime I try, the quicktime 'Q' shows, and then an error message pops up with a broken 'Q' on a piece of film. A text box then says that quicktime is missing software that is unavailable on the network. After an hour with Quicktime support, we confirmed that I have the program and it works. No solution beyond that. could I have at some point told the computer to open certain download files with the Quicktime program and was wrong? What the heck is going on> I still can't download and it has been 2 months.
RMC