Downloaded software will not function

I have downloaded four programs on-line and every one of them will not function properly.

I also had an HR Block CD that I used to try to do my taxes. After paying for the CD online, I installed the CD program and it would not work.

I tried downloading a PPT2DVD program to convert Powerpoint to a DVD to view on TV. The program (like all the others) will open but as soon as I try to implement the first step I get a message saying the program will not run and to contact tech support. I contacted PPT2DVD techs five times and have yet to get a response as to why the program will not "preprocess (the first step) my Powerpoint files.

I then tried to download and run a competitors PPT to DVD (video) and the same problem occured, as soon as the program began to work it stopped.

Any help would be appreciated.

E. Spencer