Firstly check to see the games are compatible to run on your PC - Look on the side of the box and see if they will run on your machine with your system configuration (i.e are all the games XP )
How far does the download of the game go ? - Does it appear to complete and the problems you have happen when you try to run the game ?
Is it just on one game or all games you download ?
I had a smiliar problem with on particular game, which caused me no end of grief. After unloading and downloading severl times I was giving up when I ran a DEFRAG on my HARD DRIVE . This sorted the problem...
Dont worry bout being computer clueless - if you were Bill Gates then you wouldnt be putting questions on here and I would be unable to answer !