What's really odd about this issue is that touch works fine when first starting up the machine on the login screen. I can swipe, type in my password, hit enter, etc. It's only when I log in to my account that it stops responding totally. When I boot into BIOS mode, touch works 100% fine there too - so it's not a hardware issue at the very least. Also, pen is working just fine as well, it's just touch that no longer works. I've gone into Device Manager and checked that the HID-compliant touch screen is enabled. I've tried disabling and enabling. I've tried updating its drivers - Windows says that it's up to date. I've tried uninstalling them totally. No dice. I've also reset the calibration for pen/touch input, nada. I'm otherwise fairly pleased with the Windows 10 upgrade, as it comes with a long-awaited graphics driver update that fixes brightness sliding. And I also quite like the new UIs/styling, and a new ClearType rendering of Arial that's very slick for a typography fan like myself. The touch thing is a pretty big bummer, but not a personal dealbreaker, as the pen still works and I use a Bluetooth mouse/keyboard 90% of the time. I'd still really appreciate any help or thoughts!