Using Windows 8.1 on HP machine All updates up-to-date Hardware: Microsoft Intellimouse Explorer 3.0 Explorer Folder Option selected: Single-click to open an item (point to select); Underline icon titles only when I point on them Display: Detail list (Ctrl + Shift + 6) No touch input Here's the problem: For as long as I have used windows, I can select multiple files by pressing ctrl-left mouse button. If I want to select multiple consecutive files, I move my cursor down to the last file in the list and press shift-left mouse button. If I want to select multiple files that are not listed consecutively, I move my cursor along the list of files and press ctrl-left mouse button to select each individual file. This does not work for me any longer and I do not know why. I do not have Click-lock on. Often I will press ctrl-left mouse click and the file will not select. When I move my mouse away from the file I've selected, it will UN-select. If I continue to press the CTRL key while attempting to select another file and float my mouse cursor down the list of files to select ONE single file further in the list, ALL the files in between the first file I click and the final file will become selected. Moving the mouse cursor carefully and steadily to select individual files yields varied results; sometimes I can select individual files; sometimes, I can click multiple times to select an additional file and the file will not become selected. More often than not, I will select several files and earlier files will become unselected. Extremely frustrating. I have been a Windows user since version 3.1 and this has never happened to me. I have been a Windows 8.1 user for over a year now and this is a new wrinkle. I have done system restore multiple times and it has not solved the problem. I have uninstalled Intellipoint/Microsoft Keyboard & Mouse center and reinstalled and the problem has not solved. I have checked every setting for my mouse in the mouse center and cannot see a setting that imposes this feature. Changing folder options to Double-click to open an item (single click to select) solves the problem. I am able to navigate and organize my files the way I always have. Only happens when single-click feature is enabled. Please note: I have been using the single-click select feature since Windows XP. Somehow it skips the single click part of the process and just selects by floating the cursor above the file name. Why? How can I stop it? Your guidance and actual solution to this irritant is appreciated.