Please help!!! Computer behaving poorly!!!

I hope someone can help me on this, I am faily new to
computers, so I hope this question doesn't sound stupid.
For about a week now, my computer has been acting
strange, the first thing that happened was my screen
turned black, like the monitor had turned off, when I
tried to use my mouse my curser pointer would freeze, the
monitor would turn black again, then after a few seconds
come back on, move the mouse it would freeze again ,
mouse pointer would freeze again, did this for several
seconds I would have about 10 frozen pointers all over
the place, had to shut doen by pressing the power button.
This happened 3 times, then yesterday when I went to
bring it out of hiebernation the colors on my screen we
weird and everything seemed distorted, thousands of
little x's like it was trying to fill colors in,
everything was extremely slow, and desktop icons seemed
almost shadowy, like an exray almost. I shut the computer
off with the power button, re-started it, same thing came
up so I ran my Norton 2003, took over 2 hours to
complete, no viruses found, rebooted again,and did a
system restore to last weeks date, came back normal but
it seems a little slower than normal.It seems to me that
a few files might be missing, task manager only has 2
things in it, when it used to have a lot more,I had
uninstalled 811493 already, I had no go back dates in the
norton go back, they were all gone, does anyone have any
ideas on this???
Thanks in advance
NoviceLC