Why wont my photoshop cs3 install?

Hey guys. i tried to download the free trial of photoshop to have a play around with and learn a couple of weeks ago. It worked perfectly and everything was fine. Then i had a problem with my pc and had to perform a system restore to my pc. This got rid of photoshop so i tried to download it again. I got the download assistant and tried to download photoshop again and it will download okay but then get to the install part. I t will say initialist install with a green bar underneath. The bar will get to about 2/3 full and then give me an error message saying that the instaler failed to initialize properly and to download the adobe support adviser to detect the problem. I hvave tried this and the support advisor cannot detect any problems and tells me to come to the forum. I have tried resrating my pc and choosing a number of different download locations. Please help because this is really frustrating me.