Computer Farts

I have a Windows XP system with over 700 mb ddr memory,
1.5 gighz processor and 10 gigs of harddrive space. No
brand name, it's a clone.
Problem ONE:
After using the computer for about two hours the sound
quits. After using it after a day the keyboard goes
dead. Rebooting it helps, they are both restored. What
can I do to make it quit loosing my sound and my keyboard?
Problem TWO:
I bought a burner Memorex 52x24x52 a year ago. I have
used it maybe 5 times, and not it won't burn anymore. It
says: Could not perform EndTrack, Write Error, Invalid
write state, Session fixation error, Could not perform
Fixation. These messages display on my Nero6 burner
software. What's the deal?
Help please!
I will greatly appreciate your response...
Eri