My computer used to boot in about 15 seconds, but over the past two days it has started taking 10–15 minutes to reach the sign-in screen. The displays work normally there, but after I log in, all three monitors turn black except for the mouse cursor. Restarting Windows Explorer through Task Manager brings the desktop back, but the entire system remains extremely sluggish—clicks can take minutes to respond and browsers never finish loading. I've tried several diagnostic and repair steps without success. What could be causing this, and what should I check first?
3 Answers
The first thing I’d suspect is a failing system drive, especially if Windows is taking that long to boot and every program is hanging. Open Task Manager and check the Disk column, including the active time and response time. If the drive is stuck near 100% active time or has very high response times, back up important files immediately and check its health with a SMART utility such as CrystalDiskInfo or the manufacturer’s diagnostic tool.
Back up your important documents before attempting major repairs. After that, check the drive for errors and review its SMART health data. If the drive reports warnings, bad sectors, or unusual read delays, replace it and reinstall or restore Windows rather than continuing to troubleshoot the old drive. If the drive checks out, then investigate recent Windows updates, malware scans, and graphics drivers.
Try starting Windows in Safe Mode. If it runs normally there, the cause is more likely a bad driver, startup program, or a broken recent update. You can then remove recent updates, disable unnecessary startup items, or reinstall display and storage drivers. If it is still painfully slow in Safe Mode, hardware—particularly the boot drive—becomes much more likely.
A live USB environment can also help distinguish software from hardware. If a temporary Linux or Windows recovery desktop runs reasonably well, the installed Windows setup may be damaged; if it is slow there too, suspect the drive or another hardware problem.
A dying C: drive can cause exactly this kind of behavior. Don’t wait too long to back up files, since the system may become inaccessible without warning.