For the past six months or so my desktop computer running Windows 7 64 bit would not go into the sleep mode after a specified time. I even reloaded the operating system - but preserving all the installed programs, nothing worked. Because of the inability of the latest NIS 2012 update to install I uninstalled NIS and reinstalled it to successfully do the update. In the process I also had to reinstall Ghost and Norton Utilities (all are the latest versions). Now my computer goes to sleep at the the specified time duration. My conclusion is that something in one of these programs got corrupted and prevented my computer from going into the sleep mode.
For the past six months or so my desktop computer running Windows 7 64 bit would not go into the sleep mode after a specified time. I even reloaded the operating system - but preserving all the installed programs, nothing worked. Because of the inability of the latest NIS 2012 update to install I uninstalled NIS and reinstalled it to successfully do the update. In the process I also had to reinstall Ghost and Norton Utilities (all are the latest versions). Now my computer goes to sleep at the the specified time duration. My conclusion is that something in one of these programs got corrupted and prevented my computer from going into the sleep mode.
I had no idea what the problem was so I did not post anything here. I just thought I would share this in case someone else had a similar problem.
I've had a similar experience. About a month ago my Windows 7 x64 machine quit going into sleep/hibernate mode out of the blue. It had done fine up to that point ever since I originally installed Windows 7 a year and a half ago. Then at the next full system scan after it quit hibernating, NIS 2012 reported over 60 trojan viruses in various compressed installer files. (This was a normal scan, not safe mode.) These were obviously false positives, and on the recommendation from this forum I uninstalled using the Symantec uninstaller, then reinstalled NIS 2012. Not only did the false positive problem disappear, the sleep/hibernate issue was now fixed. Could be coincidence, but I doubt it.
I am glad to hear your problem was also resolved! It appears that NIS was the problem and some setting changed to one that would not let the computer go to sleep.