I have an HP Notebook!
Are you running Vista on it? I have never had it come back out of sleep..but I did have it hang when going into sleep..
I now have Windows 7 on it and I really want to say that it was Vista that was making it hang when I would put it to sleep..Because when I put it to sleep under Windows 7 it does it in about 4 seconds, and when I resume it comes on in 4 seconds.. VERY FAST..
Have you always had this issue when first you got your PC?
The first thing I would try is to check
Device Manger and check you network adapters..to make make sure they are not set to "wake the computer"
- To do that click on the Start button, and search for Device Manger

- Look for you network adapters, Under the network adapters and right-click on the adapter.(If you have more than one adapter repeat steps 2 and 3)

- Select Properties and find the tab Power Management and make sure that the check-box for "Allow device to wake Computer" is UNCHECKED

Hope this Helps..and Happy Holidays..