I ran across this. It was a dv6000 model in the shop and here's the test. We did a factory restore and the web cam was still dead. Then it was off to HP and they swapped out the motherboard. This fix and even the troubleshooting method is not acceptable to some but let me share that we can save the old install by slipping in a new blank hard drive for the test where we install the factory restore.
I have a pavillion dv9620us with vista 32 i have tried everything to get the webcam working it used to in 2\8\08 is the last time i know it worked i tried in quickplay even reinstalled quickplay and when i did i got a message that one or more files didnot properly self register C:\programfiles\hp\quickplay\kernel\photo\climageenhance.dll invalid access to memory location also the webcam does not show up in the source area..i can find no drivers for it or software, it is also not listed in device manager at all,no imaging device at all,i dont even know what the brand name is i find nothing about it...no driver nothing that i can see.it seems like something is missing.thankyou