Unless I power off my All in 1 Pavilion desk Top it won't boot up,

[Rick218]

My Desktop all in one Pavilion wont boot up unless I disconnect the power source, once I do this it is fine until it next goes to sleep, then I have to do it again. I recently did the latest BIOS download and i thought it had fixed it,  but the fault returned 24 hrs later  

[BeemerBiker]

I suspect it is not actually going to sleep.  It appears to shut down but some device has "vetoed" the request to sleep.

Bring up the windows event viewer and look in "system" for something like "last shutdown was unexpected".  That indicates the system shutdown when you pulled the power cord.

Look also for and app that "vetoed" the shutdown, especially any entry that is marked as critical.

Also look in "applications" for anything unusual.  Unfortunately, there will be a lot of useless and misleading stuff in both system and applications.

If you click on "shutdown" is there any complaint about windows not being able to shutdown an application?

Another possibility is that a device cannot sleep.  Do you have any USB external storage or any other device attached?  The hard drive or device may not have a driver capable of telling it to sleep so it never does and the system waits forever.