That is a common issue with not specific cause. It can be a driver or malware or some bum app. It's usually expensive to figure out if you have to pay for support.
You claim nothing has changed but all the PCs with Windows I see automatically get updates from Microsoft and antivirus so can we stop thinking that nothing has changed?
Try this. Use Dell's latest drivers and BIOS for your PC. Do not install anything that is not for your PC and is not at the Dell site.
Be sure to scan with Grif's list at the next link.
A recent post found the usual and fortunately they shared what was found.
My PC has recently begun waking itself from sleep mode all on it's own.
I have checked all my devices in Device Manager and the only ones set to wake the computer from sleep are the mouse and keyboard.
I have checked the Task Scheduler and no scheduled tasks are set to wake the computer from sleep.
I have run the 'powercfg -last wake' command to see what is waking the PC, but the Wake Source comes up 0.
I have checked the event logs of Windows and can't find anything that's waking it up.
I am running a Alienware Aurora with a Intel i7 processor, 6 GB RAM with a ATI Radeon 6800 series GPU, a standard, run-of-the-mill keyboard and a Logitech M510 wireless mouse. I have an AZiO bluetooth adapter plugged in. The PC is also connected to a iOgear KVM switch. I run Windows 7 Home Premium with MSE and Ad-Aware for protection.
My PC setup hasn't changed in months and only recently has this problem cropped up, leading me to suspect a rogue program... but I haven't been able to locate it.
On a side note, my PC also sometimes has a problem restarting/shutting down while a USB flash drive or external HDD is plugged in. The PC will simply shut down Windows and hang on a black screen. The fans still run, the cooling system still runs and the power light is still on. The HDD light is not active, showing no activity suggesting that it is updating or involved in some other activity before it shuts down. It just sits there. Eventually, I have to shut it down manually using the power button.
Any insight you can provide to either problem would be much appreciated. Thank you!