My monitor works at 1920x1080. But after a reboot Windows 10 suddenly switched to 1020x768 and shows it as the recommended resolution, with the maximum of 1280x1024. The correct resolution seems to be used while Windows is booting up. How can I switch back to the correct resolution?
There are suggestions for NVidia graphics cards in several questions, but I have ATI Radeon HD 2600 XT, so I've tried to install AMD Catalyst Center as the equivalent, but it doesn't show any graphics settings in http://support.amd.com/en-us/kb-articles/Pages/GPU-10-SupportedResolutionsUnavailableforMonitor.aspx: only Pinned, Presets, Performance, and Power.
EDIT in case someone else has the same problem:
If your graphics adapter is based on an AMD Radeon™ HD 4000 Series or older, you may consider these options:
1.Upgrade to an AMD graphics card on the support product list.
2.Continue using the existing operating system.
Though I don't know what triggered it in this case, as the card has been working correctly before -- possibly some Windows update -- this seems to be what happened.
EDIT 2: it disabled sleep as well.