I have seen many treads on this subject and have tried all the repairs I can possibly try. I have a dell Latitude E5500 computer that will not hibernate or standby. The standby option is greyed out.
I checked and downloaded the newest chipset drivers from the Dell website as well as update my Bios. I have plenty of free space on my hard drive and I used a third party defragmenter to make sure I had plenty of continous room on my hard drive. If I try to turn the hibernate option on using the Command prompt I get a message saying system does not support hibernation. If I check my power option the hibernate tab is missing.
I did a update/repair using the windows XP sp3 disk thinking this might fix it. I could not find a switch in my bios to set to S4 or anything like this.
Now here comes the weirdest thing. At one point I disabled all the services and start up programs using MSconfig and for a short time I had standby as an option on shutdown and the hibernate tab in power options came back. This lasted about 2 minutes and now I can't re-create this again. This computer is not very old and came from dell with SP3 installed. Hibernate and standby did work at one time. I am a controls engineer so my computer spends a lot of time unplugged. The hibernate feature is very helpfull to me and I would greatly appricieate any help I can get in finding out why it won't work. I still have a hardware warranty on this computer so if it's hardware I can possibly have it fixed by dell but all the hardware test I have ran came back good.