Old school – win3.1 & works: Erratic dat

User gets erratic responses in Works Spreadsheets, i.e. multiple cell selection when clicking on 1 cell or using arrow keys (behaves as if F8 was pressed and ESC won’t cancel this). Also, Exit windows doesn’t work (nothing happens – system continues running) I tried another keyboard (no help). Recently removed Stealth C boot virus on this and several similar machines. All others work fine. Thank you for any guidance.