1. fyi.. for your sound card stuff in Add/Remove
=> When you uninstall via Device Manager the only thing that gets uninstalled are the drivers
=> Many sound card installers (not all) install Sound applications along with the drivers. In such case, they'll also create the Add/Remove programs entry which will uninstall any Sound card application software AS WELL as the drivers
=> So if your problem is actually the sound application vs. the driver, etc....
=> Also to do a really clean sound card re-install you want to remove any of sound card application software first as well
2. As to DVD inserted when you insert the USB flash
=> Well, thank you. I never heard of that one before! In general, there's issues between the DVD/CD device and USB flash (but hadn't heard specifically of DVD inserted)
=> I was going to also recommend uninstalling any CD/DVD creation/burning programs as well (and even more so now that i can now find links about bugs with USB sticks, e.g. for example i see AnyDVD talks about "fixing compatibility issues with memory sticks", etc.
=> What application do you use (do you anyway to reinstall it? if it's a freeware/trial version we can probably also find a copy to download online)
3. Lets check if you have a "hidden" recovery partition on your hard drive
=> Start->Run, diskmgmt.msc to open Disk Management
=> Look at the partitions defined on your hard drive. Do you see more then one? (It might not have any drive letter assigned)