I bought a second hand machine with Win7 Ultimate Sp1 64 bit preinstalled. I tried to install a printer driver for an Epson printer combo, but failed. A technician at the Epson workshop checked and said that the Win7 was faulty, because it could not detect any external device. Since the machine did not come with an installation disk, I cannot reinstall Win7. Is there any way to repair the problem in the OS without buying a disk?