Ginpit

I have a 120 gb hard drive installed as a secondary slave. It appears in Device Manager and is said to be working ok - it is obvoiusly also present in the BIOS. But when I look for it in Windows Explorer or using Control Panel it is invisible. I have tried disconnecting it in BIOS and restarting, then closing and reinstating it in BIOS to no effect. The programs which refer to this drive also cannot find it. Has anyone any ideas?