Try the hard reset procedure described here.
XPS One. Core2 Duo @ 2.2GHz. 2 GB DDR2-667. WD2500AAJS 250GB SATA. Intel GMA 3100 video. 20" WSXGA HD LCD. 2 Megapixel Webcam. 8X DVD±RW. 8-in-1 Media Reader. 802.11 a/b/g/n wireless. Integrated High Def Audio. Internal Bluetooth 2.0. NTSC/ATSC TV Tuner. Windows 7 Professional SP1.
Hi, no that did not work. In the meantime I ran the diagnostics at startup, and there neither shift key works. All other keys are fine.