I have the HP dv6910us which is all too similar. My startup and shutdown issues were tracked down to an USB connected hard disk. Here's how I fixed that.
Laptop -> USB cable -> USB drive.
Laptop -> USB cable -> USB hub -> USB cable -> USB drive.
Sorry, no. I don't expect Microsoft or HP to address why this was so. Even I don't think about it anymore.
I'm not sure what's causing this problem. Every so often, I will attempt to shut down my laptop, but it'll remain on the Shutting Down screen and not change. I leave it alone in hopes of an error message appearing so I can track down the problem, but to no avail. The screen will turn off, but my laptop remains on. All I can do is to just power down the laptop manually using the power button. I've asked HP, and they claim it has to do with static buildup... but no one else I know has ever experienced this problem. Any ideas?
I'm using a HP Pavilion dv6607nr Entertainment Notebook with Windows Vista Home Premium 32bit. The processor is an AMD Athlon(tm)64 X2 Dual-Core Processor TK-53 1.70 GHz (slow, I know haha). I also upped the RAM to 4 GB, but unfortunately a 32bit only uses 3GB. The graphics card is an NVIDIA GeForce Go 7150M. Thanks for your help in advance!