Troubleshooting sleep is something of an advanced skill. While you can start the research and there is no instant cure, there is a workaround. I do this all the time.
I change the settings from sleep to hibernate. I find it's only a few seconds difference on a good machine.
My 6 year custom built computer has developed a problem I cannot fathom or cure. It seems to be a hardware problem but I am not sure. I run XP sp3 and have only 512 mb of RAM. The computer is rarely shut down and is left on overnight, sometimes on standby or with the monitor screen off. Usually I hit a key in the morning and resume with it just where I left off the night before. Lately when I try to resume in the morning it has become unresonsive. If I click a desktop icon the text disappears from beneath it and there is no other response. Then the text disappears from the other icons and likewise with the Start button. I have to do a manual shutdown by holding down the power button and then when I restart it it works just fine the rest of the day. Does this sound like something is failing in my hardware or could it be a software problem. I have scanned with antispyware and advanced customer care and malware bytes and everything comes up clean. Also Avira scans are clean. As of now I am thinking I may need a new computer but would like to hear opinions from the experts at C-Net before I shop for one.