HP laptop keeps hanging on startup.

I realize that you've replaced memory and the hard drive, but have you tested the replacements thoroughly?  For memory, I use Memtest86+ from http://www.memtest.org/ .

For the hard drive, I usually use the hard drive manufacturer's test program, though chkdsk can be used.

Make sure everything is backed up!

As it has had this issue since you got it, have replaced under warranty. That's what warranties are for.

The computer is no longer under warranty. All parts have been thoroughly tested. Drive is a seagate tested with sea tools and memory has passed with memtest 86 as well.

It also may be worth mentioning that all the original parts passed as well but it was having the same issues although the hard drive in there before was a POS hitachi single platter design.

How can you allow the warranty expire on a PC that never worked properly from the beginning? The warranty in most countries goes for at least one year, in many even longer, so you would have had plenty of time to return it before it expired. Now it is too late you either have to live with it's problems or have it repaired by HP which will probably cost as much as a new laptop.

When something new doesn't work properly, you must make use of the warranty, and not try to fix it yourself, that is a waste of time and money.

I work in a repair shop. So obviously if it was under warranty I would have fixed it already. It was brought to me to be repaired and I had the same symptoms that the customer explained to me. Unless you have a technically helpful answer then please don't respond.

There isn't much you can do to repair laptops if the issue isn't the disk, RAM or CPU. Sometimes you can try reflowing the GPU, but the problem description doesn't point to that being the issue, and reflowing also takes time, you need the equipment and experience. You'll most probably have to change the mainboard, which is probably more expensive than a new laptop (Laptop mainboards are expensive and it is hard to get the correct model that will fit, if you get it from a 3rd party, you never know if that board is in good working order). Besides that, it all takes a lot of your time, to get the part, then manually change things (replacing a board on a laptop generally takes much more time than it would on a normal PC), and time is money which in the end the customer has to pay. Cut your's and the customers losses by telling him about how important it is to make use of warranty in the future, then have him buy a new laptop.

I appreciate the detailed response. I have done a clean install on the original drive to rule out "most" virus or driver issues. I had done as you suggested already and cloned it to a secondary drive. While the secondary drive seemed to work and boot longer it still ended up with the same issues as the original drive had. At this point if it is a mainboard issue, as seems to be what it's all pointing to, then I will give the customer a final answer. They were being indignant and I wanted to ask some peers if there was anything I was missing so they understand it isn't just me trying to convince them to put the money out for a new machine. I appreciate all the responses and if you have any final things I could attempt let me know. Thanks again.