All of a sudden, youtube videos and myspace music does not load all the way, causing them to stop midway. Why?

This just started happening and I have not had this happen since I had the computer for 4 years. I have Windows XP Home v. 2002 SP2, Pentium 4, 512 MB Ram. I have just recently installed Microsoft office 2003. I have and use Symantec Client Security to scan for viruses. I use CleanUp! to delete temporary files. As I start a youtube video, I see the video loading only 1/4th of the way, then stops. Myspace music songs play for one minute, then stops. When I press play, I see the graphic moving, as if it is on, but I hear nothing. I also have problems with my internet explorer shutting down often, and displaying a messege stating IE must shut down. I'm surprised this did not happen while I am writing this. I did use the Cleanup! and a virus scan a few minutes ago. Also, when Windows desktop comes up after booting up, sometimes my display is at 4 bit, not at 32 bit it is in now. It's like my computer is very unstable. Besides buying a new computer, does anyone have any ideas on what to do?

I used to have that problem when I had wireless internet. Sometimes I would get a low signal and things would stop working. Maybe you should try to restore your computer to an earlier time in case something happened to it recently. Also, I used to pause youtube videos at the beginning and wait until they were completely loaded before pressing play, otherwise they would never load at all. If you have wireless internet, try picking up a better signal by moving somewhere else in the house.