After doing a full system restore, it's always a good idea to go back to Microsoft and check for updates to your O/S http://v4.windowsupdate.microsoft.com/en/default.asp If you have outdated or missing drivers, they should show up when you let MS scan your PC. Barring that, I would go back to the MFR of each of your cards (audio, video, modem/NIC and etc.) and see if there are any updated versions of your current drivers.
You probably know that you can look at the current versions from the control panel/systems/device drivers windows. Go to the card (video as an example) and expand the menu, select the device & highlight it with your mouse & double click to open the info screen. It should tell you if the device is working OK and what the current driver version is.
If you've done all this already, then the next thing I'd check is the Codecs to see if you find any duplicates loaded. Here's a cut & paste from another thread of one of my posts on this:
Windows makes extensive use of CODECS (coders/decoders), as mentioned by DMR above, to support the variety of multimedia applications available. For example, video capture requires numerous codecs to encode the audio and video streams being passed to the PC. As another example, audio playback requires one codec for each type of audio format. In many cases, you may find more than one copy of the same codec on the same system. This can easily happen as various multimedia applications are installed and removed. When there is more than one instance of the same codec, conflicts may result that impair the performance of your multimedia applications. The full thread on this topic is at http://www.daniweb.com/techtalkforums/thread14015-codecs.html
Whenever you encounter trouble with audio recording, playback, capture and so on, always check for duplicate codecs under your Multimedia icon:
1- Click Start, highlight Settings, and then select Control Panel.
2- Double-click the Multimedia (may be listed as Sounds & Multimedia) icon, and then select the Devices tab.
3- Expand the Audio Compression Codecs entry and look for duplicate entries.
4- If you see duplicate entries, check the Properties for each instance and then remove the OLDER instance.
5- Apply your changes and reboot the system if necessary.
6- You can check for duplicate codecs under the other entries as well.