Back to XP, not sure how you restored, if you don't have service pack 3 installed, I would get windows updated completely.
You may want to check all your driver settings. A safe sample rate should be 44100 for projects in the driver settings in Sonar Audio setup. Don't forget to launch the ASIO for all driver control panel and set the buffer rate as low as you can get it, too low will give you pops and drop outs, too high, latency.