My thoughts...some of these may seem stupid, but should be asked:
1. You Tube runs on Adobe Flash Player 9 usually. Do you have it installed on your laptop?
2. Is it an older Compaq? Your sound card may not be able to handle newer applications.
3. Try this:
Hardware Acceleration Slider Is Set too High
If the Hardware acceleration slider is not set to None, move the Hardware acceleration slider to a notch closer to None.
To do this in Windows XP, follow these steps:
1. Click Start, point to Settings, click Control Panel, click Sounds, Speech, and Audio Devices, and then click Sounds and Audio Devices (or just Sound and Audio Devices in Classic View).
2. Click the Audio tab, and then click the Advanced button under Sound Playback.
3. Click the Performance tab, and then move the Hardware acceleration slider to a notch closer to None.
4. Click OK, and then click OK again.
5. Click Yes if you are prompted to restart your computer.
Just some things to try. Hope something works for you!
link for other assistance:
http://support.microsoft.com