Won't download files

My girlfriend has been having a lot of problems with her year old Macbook. First of all and the biggest problem, is that now she is unable to download things from online. She's tried Safari and Firefox with no luck. She was going to try Flock, but she can't download it. This applies to anything online. She can't download anything, except files from Rapidshare for some reason. Those download fine.

The second problem is that she can't watch streaming videos because even if she lets them load completely they just lag.

Another problem is with games from the Big Fish games site. She downloads them to play them and a lot of the games she just is unable to play because of lag. Now they're just games made in flash and are not resource intensive at all so I can't see the lag coming from a lack of processing power.

Her Macbook has a 2GHz processors, 1GB of RAM and a 120GB HDD.

Having the same issues on mine. Let me know if you find a fix!

Flash is very resource intensive so if the games are complex, despite perhaps not looking so, have her turn down the quality as a first attempt at fixing this. Right click the Flash game and change the quality from that menu.

As for the downloading, have you installed any download managers? Improper un-installation has caused quite a few problems with downloading files.