One beep = refresh error, two beeps = parity error, and three beeps = base 64k memory error. For all three error codes:
1. Try taking out your RAM sticks and reseating them.
2. If that does not fix the problem and you have more than one bank of RAM, take out the first bank of RAM and move the second bank of RAM to the first bank's slot (leave the first bank of RAM out and then power up your PC to test it) -you may have a bad SIMM or DIMM. If the RAM you had in bank two works fine in bank one's slot, then the RAM that was in bank one is bad.
3. If both solutions fail, replace your motherboard.